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/database/models.go

@@ -1,5 +1,3 @@
-// Package database provides data models and repository interfaces for the Vaultik backup system.
-// It includes types for files, chunks, blobs, snapshots, and their relationships.
 package database
 
 import (
@@ -13,9 +11,12 @@ import (
 // and symlink targets. This information is used to restore files with their
 // original attributes.
 type File struct {
-	ID         types.FileID     // UUID primary key
-	Path       types.FilePath   // Absolute path of the file
-	SourcePath types.SourcePath // The source directory this file came from (for restore path stripping)
+	ID   types.FileID   // UUID primary key
+	Path types.FilePath // Absolute path of the file
+
+	// SourcePath is the source directory this file came from (used for
+	// restore path stripping).
+	SourcePath types.SourcePath
 	MTime      time.Time
 	Size       int64
 	Mode       uint32
@@ -55,13 +56,16 @@ type Chunk struct {
 // The blob creation process is: chunks are accumulated -> compressed with zstd
 // -> encrypted with age -> hashed -> uploaded to S3 with the hash as filename.
 type Blob struct {
-	ID               types.BlobID   // UUID assigned when blob creation starts
-	Hash             types.BlobHash // SHA256 of final compressed+encrypted content (empty until finalized)
-	CreatedTS        time.Time      // When blob creation started
-	FinishedTS       *time.Time     // When blob was finalized (nil if still packing)
-	UncompressedSize int64          // Total size of raw chunks before compression
-	CompressedSize   int64          // Size after compression and encryption
-	UploadedTS       *time.Time     // When blob was uploaded to S3 (nil if not uploaded)
+	ID types.BlobID // UUID assigned when blob creation starts
+
+	// Hash is the SHA256 of the final compressed+encrypted content
+	// (empty until finalized).
+	Hash             types.BlobHash
+	CreatedTS        time.Time  // When blob creation started
+	FinishedTS       *time.Time // When blob was finalized (nil if still packing)
+	UncompressedSize int64      // Total size of raw chunks before compression
+	CompressedSize   int64      // Size after compression and encryption
+	UploadedTS       *time.Time // When blob was uploaded to S3 (nil if not uploaded)
 }
 
 // BlobChunk represents the mapping between blobs and the chunks they contain.
@@ -75,9 +79,10 @@ type BlobChunk struct {
 	Length    int64
 }
 
-// ChunkFile represents the reverse mapping showing which files contain a specific chunk.
-// This is used during deduplication to identify all files that share a chunk,
-// which is important for garbage collection and integrity verification.
+// ChunkFile represents the reverse mapping showing which files contain a
+// specific chunk. This is used during deduplication to identify all files
+// that share a chunk, which is important for garbage collection and
+// integrity verification.
 type ChunkFile struct {
 	ChunkHash  types.ChunkHash
 	FileID     types.FileID
@@ -87,17 +92,20 @@ type ChunkFile struct {
 
 // Snapshot represents a snapshot record in the database
 type Snapshot struct {
-	ID                   types.SnapshotID
-	Hostname             types.Hostname
-	VaultikVersion       types.Version
-	VaultikGitRevision   types.GitRevision
-	StartedAt            time.Time
-	CompletedAt          *time.Time // nil if still in progress
-	FileCount            int64
-	ChunkCount           int64
-	BlobCount            int64
-	TotalSize            int64   // Total size of all referenced files
-	BlobSize             int64   // Total size of all referenced blobs (compressed and encrypted)
+	ID                 types.SnapshotID
+	Hostname           types.Hostname
+	VaultikVersion     types.Version
+	VaultikGitRevision types.GitRevision
+	StartedAt          time.Time
+	CompletedAt        *time.Time // nil if still in progress
+	FileCount          int64
+	ChunkCount         int64
+	BlobCount          int64
+	TotalSize          int64 // Total size of all referenced files
+
+	// BlobSize is the total size of all referenced blobs (compressed and
+	// encrypted).
+	BlobSize             int64
 	BlobUncompressedSize int64   // Total uncompressed size of all referenced blobs
 	CompressionRatio     float64 // Compression ratio (BlobSize / BlobUncompressedSize)
 	CompressionLevel     int     // Compression level used for this snapshot