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/database/chunks_test.go

@@ -1,21 +1,24 @@
-package database
+package database_test
 
 import (
 	"context"
 	"testing"
 
+	"sneak.berlin/go/vaultik/internal/database"
 	"sneak.berlin/go/vaultik/internal/types"
 )
 
 func TestChunkRepository(t *testing.T) {
+	t.Parallel()
+
 	db, cleanup := setupTestDB(t)
 	defer cleanup()
 
 	ctx := context.Background()
-	repo := NewChunkRepository(db)
+	repo := database.NewChunkRepository(db)
 
 	// Test Create
-	chunk := &Chunk{
+	chunk := &database.Chunk{
 		ChunkHash: types.ChunkHash("chunkhash123"),
 		Size:      4096,
 	}
@@ -50,7 +53,7 @@ func TestChunkRepository(t *testing.T) {
 	}
 
 	// Test GetByHashes
-	chunk2 := &Chunk{
+	chunk2 := &database.Chunk{
 		ChunkHash: types.ChunkHash("chunkhash456"),
 		Size:      8192,
 	}
@@ -60,7 +63,9 @@ func TestChunkRepository(t *testing.T) {
 		t.Fatalf("failed to create second chunk: %v", err)
 	}
 
-	chunks, err := repo.GetByHashes(ctx, []string{chunk.ChunkHash.String(), chunk2.ChunkHash.String()})
+	chunks, err := repo.GetByHashes(ctx, []string{
+		chunk.ChunkHash.String(), chunk2.ChunkHash.String(),
+	})
 	if err != nil {
 		t.Fatalf("failed to get chunks by hashes: %v", err)
 	}
@@ -81,11 +86,13 @@ func TestChunkRepository(t *testing.T) {
 }
 
 func TestChunkRepositoryNotFound(t *testing.T) {
+	t.Parallel()
+
 	db, cleanup := setupTestDB(t)
 	defer cleanup()
 
 	ctx := context.Background()
-	repo := NewChunkRepository(db)
+	repo := database.NewChunkRepository(db)
 
 	// Test GetByHash with non-existent hash
 	chunk, err := repo.GetByHash(ctx, "nonexistent")