Update golangci-lint to v2.12.2 with canonical config (#62)

Updates golangci-lint to v2.12.2 everywhere it is pinned and installs the canonical `.golangci.yml`, then remediates every finding the new linter/config surfaces so `make check` is green.

## Version bump

- `Dockerfile` lint stage: `golangci/golangci-lint:v2.11.3-alpine` -> `v2.12.2-alpine` (digest-pinned, date comment updated)
- `Makefile` `deps` target: `go install` moved from the old v1 module path at `@latest` to the pinned `github.com/golangci/golangci-lint/v2/cmd/golangci-lint@v2.12.2`
- `.golangci.yml` replaced with the canonical config (v2 schema; settings under `linters.settings` so the thresholds actually apply; `default: all` with the standard six disables)
- `script/bootstrap` installs golangci-lint via the system package manager and carries no version pin, so it is unchanged
- CI (`.gitea/workflows/check.yml`) only runs `script/cibuild`, so it needed no change

## Lint remediation

The canonical config surfaced ~3,300 findings across 56k lines. All are fixed, behavior-preserving; incorporates and supersedes the per-package mechanical passes already merged to `main` (refs #61). Highlights:

- `err113`: dynamic errors replaced with package sentinels + `%w` wrapping; comparisons via `errors.Is`
- `goprintffuncname`: printf-style helpers renamed with an `f` suffix (`ui.Writer` message methods, `cli.ReportErrorf`, `database.Fatalf`) and all call sites updated
- `revive` stutter renames: `blob.Handler`, `blob.WithReader`, `blob.ChunkPosition`, `storage.URL`, `storage.Info`; missing doc comments added
- `contextcheck`/`noctx`: `context.Context` threaded through `blob.Packer` and the scanner call sites; context-aware `exec`/`sql` variants
- `funlen`/`cyclop`/`gocognit`/`dupl`: oversized and duplicated functions split into focused helpers (production and test code)
- tests: `t.Parallel()` added where safe (global logger init kept in the serial phase for `-race`), `t.TempDir()`/`t.Helper()` adopted, several suites converted to external test packages
- `gosec`: bounded integer conversions, `ReadHeaderTimeout` on the test HTTP server; remaining warnings suppressed per-site with justifications
- remaining `nolint` directives are rare, targeted, and each carries a reason (e.g. `nilnil` not-found contract in the repository layer, fx module globals, on-disk snake_case struct tags)
- removed the deprecated `log.LogOptions` alias (callers migrated to `log.Options`)

`make check` (tests with `-race`, lint, fmt-check) passes.

Co-authored-by: sneak <sneak@sneak.berlin>
Reviewed-on: #62
Co-authored-by: clawbot <clawbot@noreply.example.org>
Co-committed-by: clawbot <clawbot@noreply.example.org>

internal/vaultik/prune.go

@@ -6,7 +6,6 @@ import (
 	"fmt"
 	"strings"
 
-	"github.com/dustin/go-humanize"
 	"sneak.berlin/go/vaultik/internal/log"
 )
 
@@ -16,6 +15,14 @@ type PruneOptions struct {
 	JSON  bool
 }
 
+// errNukeRequiresForce guards the destructive remote nuke operation.
+var errNukeRequiresForce = errors.New(
+	"nuke requires --force (this deletes ALL remote snapshots and blobs)")
+
+// metadataDirName is the top-level remote directory holding snapshot
+// metadata.
+const metadataDirName = "metadata"
+
 // NukeRemote deletes every snapshot's metadata and every blob from remote
 // storage. After this returns successfully the bucket prefix is empty and
 // the next backup starts from scratch.
@@ -24,29 +31,31 @@ type PruneOptions struct {
 // confirming with the user.
 func (v *Vaultik) NukeRemote(force bool) error {
 	if !force {
-		return errors.New("nuke requires --force (this deletes ALL remote snapshots and blobs)")
+		return errNukeRequiresForce
 	}
 
-	v.UI.Begin("Removing all snapshot metadata from backup destination store.")
+	v.UI.Beginf("Removing all snapshot metadata from backup destination store.")
 
 	_, err := v.RemoveAllSnapshots(&RemoveOptions{Force: true})
 	if err != nil {
 		return fmt.Errorf("removing all snapshots: %w", err)
 	}
 
-	v.UI.Begin("Removing any blobs still present in backup destination store.")
+	v.UI.Beginf("Removing any blobs still present in backup destination store.")
 
 	err = v.PruneBlobs(&PruneOptions{Force: true})
 	if err != nil {
 		return fmt.Errorf("pruning blobs: %w", err)
 	}
 
-	v.UI.Complete("Backup destination store is now empty.")
+	v.UI.Completef("Backup destination store is now empty.")
 
 	return nil
 }
 
 // PruneBlobsResult contains the result of a blob prune operation
+//
+//nolint:tagliatelle // snake_case is the established JSON output format
 type PruneBlobsResult struct {
 	BlobsFound   int   `json:"blobs_found"`
 	BlobsDeleted int   `json:"blobs_deleted"`
@@ -113,14 +122,16 @@ func (v *Vaultik) PruneBlobs(opts *PruneOptions) error {
 		return nil
 	}
 
-	log.Info("Found unreferenced blobs", "count", len(unreferencedBlobs), "total_size", humanize.Bytes(uint64(totalSize)))
+	log.Info("Found unreferenced blobs",
+		"count", len(unreferencedBlobs), "total_size", ubytes(totalSize))
 
 	if !opts.JSON {
-		v.printfStdout("Found %d unreferenced blob(s) totaling %s\n", len(unreferencedBlobs), humanize.Bytes(uint64(totalSize)))
+		v.stdoutf("Found %d unreferenced blob(s) totaling %s\n",
+			len(unreferencedBlobs), ubytes(totalSize))
 	}
 
 	if !opts.Force && !opts.JSON {
-		v.printfStdout("\nDelete %d unreferenced blob(s)? [y/N] ", len(unreferencedBlobs))
+		v.stdoutf("\nDelete %d unreferenced blob(s)? [y/N] ", len(unreferencedBlobs))
 
 		var confirm string
 
@@ -128,7 +139,7 @@ func (v *Vaultik) PruneBlobs(opts *PruneOptions) error {
 		if err != nil {
 			v.printlnStdout("Cancelled")
 
-			return nil
+			return nil //nolint:nilerr // read failure means no confirmation
 		}
 
 		if strings.ToLower(confirm) != "y" {
@@ -144,16 +155,18 @@ func (v *Vaultik) PruneBlobs(opts *PruneOptions) error {
 		return v.outputPruneBlobsJSON(result)
 	}
 
-	v.printfStdout("\nDeleted %d blob(s) totaling %s\n", result.BlobsDeleted, humanize.Bytes(uint64(result.BytesFreed)))
+	v.stdoutf("\nDeleted %d blob(s) totaling %s\n",
+		result.BlobsDeleted, ubytes(result.BytesFreed))
 
 	if result.BlobsFailed > 0 {
-		v.printfStdout("Failed to delete %d blob(s)\n", result.BlobsFailed)
+		v.stdoutf("Failed to delete %d blob(s)\n", result.BlobsFailed)
 	}
 
 	return nil
 }
 
-// collectReferencedBlobs downloads all manifests and returns the set of referenced blob hashes
+// collectReferencedBlobs downloads all manifests and returns the set of
+// referenced blob hashes.
 func (v *Vaultik) collectReferencedBlobs() (map[string]bool, error) {
 	log.Info("Listing remote snapshots")
 	// IDs returned by listUniqueSnapshotIDs are remote keys (hashed
@@ -185,7 +198,8 @@ func (v *Vaultik) collectReferencedBlobs() (map[string]bool, error) {
 		manifestCount++
 	}
 
-	log.Info("Processed manifests", "count", manifestCount, "unique_blobs_referenced", len(allBlobsReferenced))
+	log.Info("Processed manifests",
+		"count", manifestCount, "unique_blobs_referenced", len(allBlobsReferenced))
 
 	return allBlobsReferenced, nil
 }
@@ -203,8 +217,10 @@ func (v *Vaultik) listUniqueSnapshotIDs() ([]string, error) {
 		}
 
 		parts := strings.Split(object.Key, "/")
-		if len(parts) >= 2 && parts[0] == "metadata" && parts[1] != "" {
-			if strings.HasSuffix(object.Key, "/") || strings.Contains(object.Key, "/manifest.json.zst") {
+		if len(parts) >= minSnapshotIDParts &&
+			parts[0] == metadataDirName && parts[1] != "" {
+			if strings.HasSuffix(object.Key, "/") ||
+				strings.Contains(object.Key, "/manifest.json.zst") {
 				snapshotID := parts[1]
 				if !seen[snapshotID] {
 					seen[snapshotID] = true
@@ -230,7 +246,7 @@ func (v *Vaultik) listAllRemoteBlobs() (map[string]int64, error) {
 		}
 
 		parts := strings.Split(object.Key, "/")
-		if len(parts) == 4 && parts[0] == "blobs" {
+		if len(parts) == blobKeyParts && parts[0] == "blobs" {
 			allBlobs[parts[3]] = object.Size
 		}
 	}
@@ -240,8 +256,11 @@ func (v *Vaultik) listAllRemoteBlobs() (map[string]int64, error) {
 	return allBlobs, nil
 }
 
-// findUnreferencedBlobs returns blob hashes not referenced by any manifest and their total size
-func (v *Vaultik) findUnreferencedBlobs(allBlobs map[string]int64, referenced map[string]bool) ([]string, int64) {
+// findUnreferencedBlobs returns blob hashes not referenced by any
+// manifest and their total size.
+func (v *Vaultik) findUnreferencedBlobs(
+	allBlobs map[string]int64, referenced map[string]bool,
+) ([]string, int64) {
 	var (
 		unreferenced []string
 		totalSize    int64
@@ -257,8 +276,11 @@ func (v *Vaultik) findUnreferencedBlobs(allBlobs map[string]int64, referenced ma
 	return unreferenced, totalSize
 }
 
-// deleteUnreferencedBlobs deletes the given blobs from storage and populates the result
-func (v *Vaultik) deleteUnreferencedBlobs(unreferencedBlobs []string, allBlobs map[string]int64, result *PruneBlobsResult) {
+// deleteUnreferencedBlobs deletes the given blobs from storage and
+// populates the result.
+func (v *Vaultik) deleteUnreferencedBlobs(
+	unreferencedBlobs []string, allBlobs map[string]int64, result *PruneBlobsResult,
+) {
 	log.Info("Deleting unreferenced blobs")
 
 	for i, hash := range unreferencedBlobs {
@@ -274,11 +296,12 @@ func (v *Vaultik) deleteUnreferencedBlobs(unreferencedBlobs []string, allBlobs m
 		result.BlobsDeleted++
 		result.BytesFreed += allBlobs[hash]
 
-		if (i+1)%100 == 0 || i == len(unreferencedBlobs)-1 {
+		if (i+1)%progressLogEvery == 0 || i == len(unreferencedBlobs)-1 {
 			log.Info("Deletion progress",
 				"deleted", i+1,
 				"total", len(unreferencedBlobs),
-				"percent", fmt.Sprintf("%.1f%%", float64(i+1)/float64(len(unreferencedBlobs))*100),
+				"percent", fmt.Sprintf("%.1f%%",
+					float64(i+1)/float64(len(unreferencedBlobs))*percentScale),
 			)
 		}
 	}
@@ -287,7 +310,7 @@ func (v *Vaultik) deleteUnreferencedBlobs(unreferencedBlobs []string, allBlobs m
 
 	log.Info("Prune complete",
 		"deleted_count", result.BlobsDeleted,
-		"deleted_size", humanize.Bytes(uint64(result.BytesFreed)),
+		"deleted_size", ubytes(result.BytesFreed),
 		"failed", result.BlobsFailed,
 	)
 }