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/snapshot/snapshot_test.go

@@ -1,3 +1,4 @@
+//nolint:testpackage // exercises unexported SnapshotManager internals
 package snapshot
 
 import (
@@ -37,9 +38,65 @@ func copyFile(fs afero.Fs, src, dst string) error {
 	return err
 }
 
+// verifyCleanedDB opens the cleaned database and checks that the kept
+// snapshot survived while the orphan file and chunk were removed.
+func verifyCleanedDB(
+	ctx context.Context,
+	t *testing.T,
+	tempDBPath, snapshotID string,
+	file *database.File,
+	chunk *database.Chunk,
+) {
+	t.Helper()
+
+	cleanedDB, err := database.New(ctx, tempDBPath)
+	if err != nil {
+		t.Fatalf("failed to open cleaned database: %v", err)
+	}
+	defer func() {
+		err := cleanedDB.Close()
+		if err != nil {
+			t.Errorf("failed to close database: %v", err)
+		}
+	}()
+
+	cleanedRepos := database.NewRepositories(cleanedDB)
+
+	// Verify snapshot exists
+	verifySnapshot, err := cleanedRepos.Snapshots.GetByID(ctx, snapshotID)
+	if err != nil {
+		t.Fatalf("failed to get snapshot: %v", err)
+	}
+
+	if verifySnapshot == nil {
+		t.Error("snapshot should exist")
+	}
+
+	// Verify orphan file is gone
+	f, err := cleanedRepos.Files.GetByPath(ctx, file.Path.String())
+	if err != nil {
+		t.Fatalf("failed to check file: %v", err)
+	}
+
+	if f != nil {
+		t.Error("orphan file should not exist")
+	}
+
+	// Verify orphan chunk is gone
+	c, err := cleanedRepos.Chunks.GetByHash(ctx, chunk.ChunkHash.String())
+	if err != nil {
+		t.Fatalf("failed to check chunk: %v", err)
+	}
+
+	if c != nil {
+		t.Error("orphan chunk should not exist")
+	}
+}
+
 func TestCleanSnapshotDBEmptySnapshot(t *testing.T) {
 	// Initialize logger
 	log.Initialize(log.Config{})
+	t.Parallel()
 
 	ctx := context.Background()
 	fs := afero.NewOsFs()
@@ -85,13 +142,16 @@ func TestCleanSnapshotDBEmptySnapshot(t *testing.T) {
 	}
 
 	// Close the database
-	if err := db.Close(); err != nil {
+	err = db.Close()
+	if err != nil {
 		t.Fatalf("failed to close database: %v", err)
 	}
 
 	// Copy database
 	tempDBPath := filepath.Join(tempDir, "temp.db")
-	if err := copyFile(fs, dbPath, tempDBPath); err != nil {
+
+	err = copyFile(fs, dbPath, tempDBPath)
+	if err != nil {
 		t.Fatalf("failed to copy database: %v", err)
 	}
 
@@ -105,58 +165,20 @@ func TestCleanSnapshotDBEmptySnapshot(t *testing.T) {
 		config: cfg,
 		fs:     fs,
 	}
-	if _, err := sm.cleanSnapshotDB(ctx, tempDBPath, snapshot.ID.String()); err != nil {
+
+	_, err = sm.cleanSnapshotDB(ctx, tempDBPath, snapshot.ID.String())
+	if err != nil {
 		t.Fatalf("failed to clean snapshot database: %v", err)
 	}
 
 	// Verify the cleaned database
-	cleanedDB, err := database.New(ctx, tempDBPath)
-	if err != nil {
-		t.Fatalf("failed to open cleaned database: %v", err)
-	}
-	defer func() {
-		err := cleanedDB.Close()
-		if err != nil {
-			t.Errorf("failed to close database: %v", err)
-		}
-	}()
-
-	cleanedRepos := database.NewRepositories(cleanedDB)
-
-	// Verify snapshot exists
-	verifySnapshot, err := cleanedRepos.Snapshots.GetByID(ctx, snapshot.ID.String())
-	if err != nil {
-		t.Fatalf("failed to get snapshot: %v", err)
-	}
-
-	if verifySnapshot == nil {
-		t.Error("snapshot should exist")
-	}
-
-	// Verify orphan file is gone
-	f, err := cleanedRepos.Files.GetByPath(ctx, file.Path.String())
-	if err != nil {
-		t.Fatalf("failed to check file: %v", err)
-	}
-
-	if f != nil {
-		t.Error("orphan file should not exist")
-	}
-
-	// Verify orphan chunk is gone
-	c, err := cleanedRepos.Chunks.GetByHash(ctx, chunk.ChunkHash.String())
-	if err != nil {
-		t.Fatalf("failed to check chunk: %v", err)
-	}
-
-	if c != nil {
-		t.Error("orphan chunk should not exist")
-	}
+	verifyCleanedDB(ctx, t, tempDBPath, snapshot.ID.String(), file, chunk)
 }
 
 func TestCleanSnapshotDBNonExistentSnapshot(t *testing.T) {
 	// Initialize logger
 	log.Initialize(log.Config{})
+	t.Parallel()
 
 	ctx := context.Background()
 	fs := afero.NewOsFs()
@@ -171,13 +193,16 @@ func TestCleanSnapshotDBNonExistentSnapshot(t *testing.T) {
 	}
 
 	// Close immediately
-	if err := db.Close(); err != nil {
+	err = db.Close()
+	if err != nil {
 		t.Fatalf("failed to close database: %v", err)
 	}
 
 	// Copy database
 	tempDBPath := filepath.Join(tempDir, "temp.db")
-	if err := copyFile(fs, dbPath, tempDBPath); err != nil {
+
+	err = copyFile(fs, dbPath, tempDBPath)
+	if err != nil {
 		t.Fatalf("failed to copy database: %v", err)
 	}