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/storage/module.go

@@ -10,9 +10,17 @@ import (
 	"sneak.berlin/go/vaultik/internal/s3"
 )
 
+// defaultS3Region is used when neither the URL nor the config specify one.
+const defaultS3Region = "us-east-1"
+
+// defaultS3Endpoint is the AWS endpoint used when none is configured.
+const defaultS3Endpoint = "s3.amazonaws.com"
+
 // Module exports storage functionality as an fx module.
 // It provides a Storer implementation based on the configured storage URL
 // or falls back to legacy S3 configuration.
+//
+//nolint:gochecknoglobals // fx module definitions are package globals
 var Module = fx.Module("storage",
 	fx.Provide(NewStorer),
 )
@@ -20,6 +28,8 @@ var Module = fx.Module("storage",
 // NewStorer creates a Storer based on configuration.
 // If StorageURL is set, it uses URL-based configuration.
 // Otherwise, it falls back to legacy S3 configuration.
+//
+//nolint:ireturn // fx provider intentionally returns the Storer interface
 func NewStorer(cfg *config.Config) (Storer, error) {
 	if cfg.StorageURL != "" {
 		return storerFromURL(cfg.StorageURL, cfg)
@@ -28,6 +38,7 @@ func NewStorer(cfg *config.Config) (Storer, error) {
 	return storerFromLegacyS3Config(cfg)
 }
 
+//nolint:ireturn // factory intentionally returns the Storer interface
 func storerFromURL(rawURL string, cfg *config.Config) (Storer, error) {
 	parsed, err := ParseStorageURL(rawURL)
 	if err != nil {
@@ -35,59 +46,74 @@ func storerFromURL(rawURL string, cfg *config.Config) (Storer, error) {
 	}
 
 	switch parsed.Scheme {
-	case "file":
+	case schemeFile:
 		return NewFileStorer(parsed.Prefix)
 
-	case "s3":
-		// Build endpoint URL
-		endpoint := parsed.Endpoint
-		if endpoint == "" {
-			endpoint = "s3.amazonaws.com"
-		}
+	case schemeS3:
+		return storerFromParsedS3URL(parsed, cfg)
 
-		// Add protocol if not present
-		if parsed.UseSSL && !strings.HasPrefix(endpoint, "https://") && !strings.HasPrefix(endpoint, "http://") {
-			endpoint = "https://" + endpoint
-		} else if !parsed.UseSSL && !strings.HasPrefix(endpoint, "http://") && !strings.HasPrefix(endpoint, "https://") {
-			endpoint = "http://" + endpoint
-		}
-
-		region := parsed.Region
-		if region == "" {
-			region = cfg.S3.Region
-			if region == "" {
-				region = "us-east-1"
-			}
-		}
-
-		// Credentials come from config (not URL for security)
-		client, err := s3.NewClient(context.Background(), s3.Config{
-			Endpoint:        endpoint,
-			Bucket:          parsed.Bucket,
-			Prefix:          parsed.Prefix,
-			AccessKeyID:     cfg.S3.AccessKeyID,
-			SecretAccessKey: cfg.S3.SecretAccessKey,
-			Region:          region,
-		})
-		if err != nil {
-			return nil, fmt.Errorf("creating S3 client: %w", err)
-		}
-
-		return NewS3Storer(client), nil
-
-	case "rclone":
-		return NewRcloneStorer(context.Background(), parsed.RcloneRemote, parsed.Prefix)
+	case schemeRclone:
+		return NewRcloneStorer(
+			context.Background(), parsed.RcloneRemote, parsed.Prefix)
 
 	default:
-		return nil, fmt.Errorf("unsupported storage scheme: %s", parsed.Scheme)
+		return nil, fmt.Errorf("%w: %s", ErrUnsupportedStorage, parsed.Scheme)
 	}
 }
 
+// storerFromParsedS3URL builds an S3 storer from a parsed s3:// URL,
+// filling endpoint protocol and region defaults from the config.
+//
+//nolint:ireturn // factory intentionally returns the Storer interface
+func storerFromParsedS3URL(parsed *URL, cfg *config.Config) (Storer, error) {
+	// Build endpoint URL
+	endpoint := parsed.Endpoint
+	if endpoint == "" {
+		endpoint = defaultS3Endpoint
+	}
+
+	// Add protocol if not present
+	hasProtocol := strings.HasPrefix(endpoint, "https://") ||
+		strings.HasPrefix(endpoint, "http://")
+	if !hasProtocol {
+		if parsed.UseSSL {
+			endpoint = "https://" + endpoint
+		} else {
+			endpoint = "http://" + endpoint
+		}
+	}
+
+	region := parsed.Region
+	if region == "" {
+		region = cfg.S3.Region
+		if region == "" {
+			region = defaultS3Region
+		}
+	}
+
+	// Credentials come from config (not URL for security)
+	client, err := s3.NewClient(context.Background(), s3.Config{
+		Endpoint:        endpoint,
+		Bucket:          parsed.Bucket,
+		Prefix:          parsed.Prefix,
+		AccessKeyID:     cfg.S3.AccessKeyID,
+		SecretAccessKey: cfg.S3.SecretAccessKey,
+		Region:          region,
+	})
+	if err != nil {
+		return nil, fmt.Errorf("creating S3 client: %w", err)
+	}
+
+	return NewS3Storer(client), nil
+}
+
+//nolint:ireturn // factory intentionally returns the Storer interface
 func storerFromLegacyS3Config(cfg *config.Config) (Storer, error) {
 	endpoint := cfg.S3.Endpoint
 
 	// Ensure protocol is present
-	if !strings.HasPrefix(endpoint, "http://") && !strings.HasPrefix(endpoint, "https://") {
+	if !strings.HasPrefix(endpoint, "http://") &&
+		!strings.HasPrefix(endpoint, "https://") {
 		if cfg.S3.UseSSL {
 			endpoint = "https://" + endpoint
 		} else {
@@ -97,7 +123,7 @@ func storerFromLegacyS3Config(cfg *config.Config) (Storer, error) {
 
 	region := cfg.S3.Region
 	if region == "" {
-		region = "us-east-1"
+		region = defaultS3Region
 	}
 
 	client, err := s3.NewClient(context.Background(), s3.Config{