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/rclone.go

@@ -69,7 +69,8 @@ func (r *RcloneStorer) Put(ctx context.Context, key string, data io.Reader) erro
 	}
 
 	// Upload the object
-	_, err = operations.Rcat(ctx, r.fsys, key, io.NopCloser(bytes.NewReader(buf)), time.Now(), nil)
+	_, err = operations.Rcat(ctx, r.fsys, key,
+		io.NopCloser(bytes.NewReader(buf)), time.Now(), nil)
 	if err != nil {
 		return fmt.Errorf("uploading object: %w", err)
 	}
@@ -78,7 +79,10 @@ func (r *RcloneStorer) Put(ctx context.Context, key string, data io.Reader) erro
 }
 
 // PutWithProgress stores data with progress reporting.
-func (r *RcloneStorer) PutWithProgress(ctx context.Context, key string, data io.Reader, size int64, progress ProgressCallback) error {
+func (r *RcloneStorer) PutWithProgress(
+	ctx context.Context, key string, data io.Reader,
+	_ int64, progress ProgressCallback,
+) error {
 	// Wrap reader with progress tracking
 	pr := &progressReader{
 		reader:   data,
@@ -155,7 +159,8 @@ func (r *RcloneStorer) Delete(ctx context.Context, key string) error {
 		return fmt.Errorf("getting object: %w", err)
 	}
 
-	if err := obj.Remove(ctx); err != nil {
+	err = obj.Remove(ctx)
+	if err != nil {
 		return fmt.Errorf("removing object: %w", err)
 	}
 
@@ -180,7 +185,9 @@ func (r *RcloneStorer) List(ctx context.Context, prefix string) ([]string, error
 }
 
 // ListStream returns a channel of ObjectInfo for large result sets.
-func (r *RcloneStorer) ListStream(ctx context.Context, prefix string) <-chan ObjectInfo {
+func (r *RcloneStorer) ListStream(
+	ctx context.Context, prefix string,
+) <-chan ObjectInfo {
 	ch := make(chan ObjectInfo)
 
 	go func() {
@@ -211,14 +218,14 @@ func (r *RcloneStorer) ListStream(ctx context.Context, prefix string) <-chan Obj
 }
 
 // Info returns human-readable storage location information.
-func (r *RcloneStorer) Info() StorageInfo {
+func (r *RcloneStorer) Info() Info {
 	location := r.remote
 	if r.path != "" {
 		location += ":" + r.path
 	}
 
-	return StorageInfo{
-		Type:     "rclone",
+	return Info{
+		Type:     schemeRclone,
 		Location: location,
 	}
 }