fix(docs/storage): resolve FLAW-02, remove unused docDir and update documentation for pure database architecture

internal/storage/sqlite.go

@@ -21,19 +21,15 @@ import (
 
 type Store struct {
 	db     *sql.DB
-	docDir string
 	initMu sync.Mutex
 }
 
 func NewStore(dbPath string) (*Store, error) {
-	var docDir string
 	if dbPath != ":memory:" && !strings.HasPrefix(dbPath, "file:") {
 		dir := filepath.Dir(dbPath)
 		if err := os.MkdirAll(dir, 0755); err != nil {
 			return nil, fmt.Errorf("failed to create data directory %s: %w", dir, err)
 		}
-		docDir = filepath.Join(dir, "workspace")
-		_ = os.MkdirAll(docDir, 0755)
 	}
 
 	dsn := dbPath
@@ -49,7 +45,7 @@ func NewStore(dbPath string) (*Store, error) {
 	db.SetMaxOpenConns(8)
 	db.SetMaxIdleConns(4)
 
-	store := &Store{db: db, docDir: docDir}
+	store := &Store{db: db}
 	if err := store.migrate(); err != nil {
 		return nil, fmt.Errorf("failed to run migrations: %w", err)
 	}