Remediate all lint findings under the canonical golangci-lint config

Fix every finding surfaced by the canonical .golangci.yml with
golangci-lint v2.12.2 (refs #61), behavior-preserving throughout:

- err113: dynamic errors replaced with package-level sentinels and %w
  wrapping; direct comparisons converted to errors.Is
- goprintffuncname: printf-style helpers renamed with an f suffix
  (ui.Writer message methods, cli.ReportErrorf, database.Fatalf,
  vaultik stdoutf) and all call sites updated
- revive: stuttering type names renamed (blob.Handler, blob.WithReader,
  blob.ChunkPosition, storage.URL, storage.Info), doc comments added,
  unused parameters blanked, package comments added
- contextcheck/noctx: ctx threaded through blob.Packer
  (AddChunk/Flush/FinalizeBlob/PackChunks) and scanner call sites;
  context-aware exec and sql variants used
- funlen/cyclop/gocognit/nestif/dupl: oversized or duplicated
  functions split into focused helpers across production and test code
- paralleltest/tparallel/thelper/usetesting/testpackage: tests
  parallelized where safe (global log.Initialize kept in the serial
  phase), helpers marked, t.TempDir adopted, external test packages
  where only exported API is used
- gosec: integer conversions clamped or justified, header timeouts
  added, remaining findings suppressed with per-site justifications
- mnd/goconst/lll/wsl_v5/nlreturn/noinlineerr/errcheck and other
  mechanical findings fixed directly

Remove the deprecated log.LogOptions alias (callers migrated to
log.Options). make check is green.

internal/storage/file.go

@@ -42,18 +42,19 @@ func (f *FileStorer) SetFilesystem(fs afero.Fs) {
 	f.fs = fs
 }
 
-// fullPath returns the full filesystem path for a key.
-func (f *FileStorer) fullPath(key string) string {
-	return filepath.Join(f.basePath, key)
-}
+// storageDirPerm is the mode used for directories created under the
+// storage base path.
+const storageDirPerm = 0o755
 
 // Put stores data at the specified key.
-func (f *FileStorer) Put(ctx context.Context, key string, data io.Reader) error {
+func (f *FileStorer) Put(_ context.Context, key string, data io.Reader) error {
 	path := f.fullPath(key)
 
 	// Create parent directories
 	dir := filepath.Dir(path)
-	if err := f.fs.MkdirAll(dir, 0755); err != nil {
+
+	err := f.fs.MkdirAll(dir, storageDirPerm)
+	if err != nil {
 		return fmt.Errorf("creating directories: %w", err)
 	}
 
@@ -63,7 +64,8 @@ func (f *FileStorer) Put(ctx context.Context, key string, data io.Reader) error
 	}
 	defer func() { _ = file.Close() }()
 
-	if _, err := io.Copy(file, data); err != nil {
+	_, err = io.Copy(file, data)
+	if err != nil {
 		return fmt.Errorf("writing file: %w", err)
 	}
 
@@ -71,12 +73,17 @@ func (f *FileStorer) Put(ctx context.Context, key string, data io.Reader) error
 }
 
 // PutWithProgress stores data with progress reporting.
-func (f *FileStorer) PutWithProgress(ctx context.Context, key string, data io.Reader, size int64, progress ProgressCallback) error {
+func (f *FileStorer) PutWithProgress(
+	_ context.Context, key string, data io.Reader,
+	_ int64, progress ProgressCallback,
+) error {
 	path := f.fullPath(key)
 
 	// Create parent directories
 	dir := filepath.Dir(path)
-	if err := f.fs.MkdirAll(dir, 0755); err != nil {
+
+	err := f.fs.MkdirAll(dir, storageDirPerm)
+	if err != nil {
 		return fmt.Errorf("creating directories: %w", err)
 	}
 
@@ -92,7 +99,8 @@ func (f *FileStorer) PutWithProgress(ctx context.Context, key string, data io.Re
 		callback: progress,
 	}
 
-	if _, err := io.Copy(pw, data); err != nil {
+	_, err = io.Copy(pw, data)
+	if err != nil {
 		return fmt.Errorf("writing file: %w", err)
 	}
 
@@ -100,7 +108,7 @@ func (f *FileStorer) PutWithProgress(ctx context.Context, key string, data io.Re
 }
 
 // Get retrieves data from the specified key.
-func (f *FileStorer) Get(ctx context.Context, key string) (io.ReadCloser, error) {
+func (f *FileStorer) Get(_ context.Context, key string) (io.ReadCloser, error) {
 	path := f.fullPath(key)
 
 	file, err := f.fs.Open(path)
@@ -116,7 +124,7 @@ func (f *FileStorer) Get(ctx context.Context, key string) (io.ReadCloser, error)
 }
 
 // Stat returns metadata about an object without retrieving its contents.
-func (f *FileStorer) Stat(ctx context.Context, key string) (*ObjectInfo, error) {
+func (f *FileStorer) Stat(_ context.Context, key string) (*ObjectInfo, error) {
 	path := f.fullPath(key)
 
 	info, err := f.fs.Stat(path)
@@ -135,7 +143,7 @@ func (f *FileStorer) Stat(ctx context.Context, key string) (*ObjectInfo, error)
 }
 
 // Delete removes an object.
-func (f *FileStorer) Delete(ctx context.Context, key string) error {
+func (f *FileStorer) Delete(_ context.Context, key string) error {
 	path := f.fullPath(key)
 
 	err := f.fs.Remove(path)
@@ -231,7 +239,7 @@ func (f *FileStorer) ListStream(ctx context.Context, prefix string) <-chan Objec
 			if err != nil {
 				ch <- ObjectInfo{Err: err}
 
-				return nil // Continue walking despite errors
+				return nil //nolint:nilerr // continue walking despite errors
 			}
 
 			if !info.IsDir() {
@@ -257,13 +265,18 @@ func (f *FileStorer) ListStream(ctx context.Context, prefix string) <-chan Objec
 }
 
 // Info returns human-readable storage location information.
-func (f *FileStorer) Info() StorageInfo {
-	return StorageInfo{
-		Type:     "file",
+func (f *FileStorer) Info() Info {
+	return Info{
+		Type:     schemeFile,
 		Location: f.basePath,
 	}
 }
 
+// fullPath returns the full filesystem path for a key.
+func (f *FileStorer) fullPath(key string) string {
+	return filepath.Join(f.basePath, key)
+}
+
 // progressWriter wraps an io.Writer to track write progress.
 type progressWriter struct {
 	writer   io.Writer