feat(chunking): add AST-aware code chunking for Go, Python, TypeScript

- [x] Add language-specific chunkers with AST parsing (Go, Python, TypeScript)
- [x] Implement chunking manager to dispatch files to appropriate chunkers
- [x] Integrate code chunks into vector sync for semantic search
- [x] Add tree-sitter dependency for Python/TypeScript parsing
- [x] Reorder struct fields for consistency across codebase
- [x] Rename error variables to follow Go conventions (err → unmarshalErr, etc.)
- [x] Add code chunk metadata to vector documents (language, symbol name, line ranges)
- [x] Update worker service to initialize chunking pipeline with all three languages

internal/db/sqlite/conflict.go

@@ -182,13 +182,13 @@ func (s *ConflictStore) CleanupSupersededObservations(ctx context.Context, proje
 	var toDelete []int64
 	for rows.Next() {
 		var id int64
-		if err := rows.Scan(&id); err != nil {
-			return nil, err
+		if scanErr := rows.Scan(&id); scanErr != nil {
+			return nil, scanErr
 		}
 		toDelete = append(toDelete, id)
 	}
-	if err := rows.Err(); err != nil {
-		return nil, err
+	if rowsErr := rows.Err(); rowsErr != nil {
+		return nil, rowsErr
 	}
 
 	if len(toDelete) == 0 {
@@ -197,8 +197,8 @@ func (s *ConflictStore) CleanupSupersededObservations(ctx context.Context, proje
 
 	// Delete the conflict records first (due to foreign key constraints)
 	for _, obsID := range toDelete {
-		if err := s.DeleteConflictsByObservationID(ctx, obsID); err != nil {
-			return nil, err
+		if delErr := s.DeleteConflictsByObservationID(ctx, obsID); delErr != nil {
+			return nil, delErr
 		}
 	}
 

internal/db/sqlite/helpers_test.go

@@ -54,14 +54,14 @@ func TestNullInt(t *testing.T) {
 func TestRepeatPlaceholders(t *testing.T) {
 	tests := []struct {
 		name     string
-		n        int
 		expected string
+		n        int
 	}{
-		{"zero", 0, ""},
-		{"negative", -1, ""},
-		{"one", 1, ", ?"},
-		{"two", 2, ", ?, ?"},
-		{"three", 3, ", ?, ?, ?"},
+		{name: "zero", n: 0, expected: ""},
+		{name: "negative", n: -1, expected: ""},
+		{name: "one", n: 1, expected: ", ?"},
+		{name: "two", n: 2, expected: ", ?, ?"},
+		{name: "three", n: 3, expected: ", ?, ?, ?"},
 	}
 
 	for _, tt := range tests {

internal/db/sqlite/migrations.go

@@ -9,9 +9,9 @@ import (
 
 // Migration represents a database schema migration.
 type Migration struct {
-	Version int
 	Name    string
 	SQL     string
+	Version int
 }
 
 // Migrations is the list of all database migrations in order.
@@ -539,11 +539,11 @@ func (m *MigrationManager) ApplyMigration(migration Migration) error {
 	if err != nil {
 		return fmt.Errorf("begin transaction: %w", err)
 	}
-	defer tx.Rollback()
+	defer func() { _ = tx.Rollback() }()
 
 	// Execute migration SQL
-	if _, err := tx.Exec(migration.SQL); err != nil {
-		return fmt.Errorf("execute migration %d (%s): %w", migration.Version, migration.Name, err)
+	if _, execErr := tx.Exec(migration.SQL); execErr != nil {
+		return fmt.Errorf("execute migration %d (%s): %w", migration.Version, migration.Name, execErr)
 	}
 
 	// Record migration

internal/db/sqlite/observation.go

@@ -585,13 +585,13 @@ func (s *ObservationStore) CleanupOldObservations(ctx context.Context, project s
 	var toDelete []int64
 	for rows.Next() {
 		var id int64
-		if err := rows.Scan(&id); err != nil {
-			return nil, err
+		if scanErr := rows.Scan(&id); scanErr != nil {
+			return nil, scanErr
 		}
 		toDelete = append(toDelete, id)
 	}
-	if err := rows.Err(); err != nil {
-		return nil, err
+	if rowsErr := rows.Err(); rowsErr != nil {
+		return nil, rowsErr
 	}
 
 	if len(toDelete) == 0 {

internal/db/sqlite/observation_test.go

@@ -65,10 +65,10 @@ func (s *ObservationStoreSuite) TestStoreObservation_TableDriven() {
 	ctx := context.Background()
 
 	tests := []struct {
+		obs          *models.ParsedObservation
 		name         string
 		sdkSessionID string
 		project      string
-		obs          *models.ParsedObservation
 		promptNum    int
 		tokens       int64
 		wantErr      bool
@@ -308,8 +308,8 @@ func (s *ObservationStoreSuite) TestGetObservationsByIDs() {
 
 	tests := []struct {
 		name      string
-		queryIDs  []int64
 		orderBy   string
+		queryIDs  []int64
 		limit     int
 		wantCount int
 	}{

internal/db/sqlite/prompt.go

@@ -102,13 +102,13 @@ func (s *PromptStore) CleanupOldPrompts(ctx context.Context) ([]int64, error) {
 	var toDelete []int64
 	for rows.Next() {
 		var id int64
-		if err := rows.Scan(&id); err != nil {
-			return nil, err
+		if scanErr := rows.Scan(&id); scanErr != nil {
+			return nil, scanErr
 		}
 		toDelete = append(toDelete, id)
 	}
-	if err := rows.Err(); err != nil {
-		return nil, err
+	if rowsErr := rows.Err(); rowsErr != nil {
+		return nil, rowsErr
 	}
 
 	if len(toDelete) == 0 {

internal/db/sqlite/prompt_test.go

@@ -261,14 +261,14 @@ func TestPromptStore_SaveMultiplePrompts(t *testing.T) {
 
 	tests := []struct {
 		claudeSessionID string
-		promptNum       int
 		text            string
+		promptNum       int
 		matches         int
 	}{
-		{"claude-1", 1, "First prompt", 5},
-		{"claude-1", 2, "Second prompt", 3},
-		{"claude-2", 1, "Third prompt", 0},
-		{"claude-1", 3, "Fourth prompt", 10},
+		{claudeSessionID: "claude-1", promptNum: 1, text: "First prompt", matches: 5},
+		{claudeSessionID: "claude-1", promptNum: 2, text: "Second prompt", matches: 3},
+		{claudeSessionID: "claude-2", promptNum: 1, text: "Third prompt", matches: 0},
+		{claudeSessionID: "claude-1", promptNum: 3, text: "Fourth prompt", matches: 10},
 	}
 
 	for _, tt := range tests {

internal/db/sqlite/scoring.go

@@ -71,7 +71,7 @@ func (s *ObservationStore) UpdateImportanceScores(ctx context.Context, scores ma
 	if err != nil {
 		return err
 	}
-	defer tx.Rollback()
+	defer func() { _ = tx.Rollback() }()
 
 	now := time.Now().UnixMilli()
 	stmt, err := tx.PrepareContext(ctx, `
@@ -171,7 +171,7 @@ func (s *ObservationStore) UpdateConceptWeights(ctx context.Context, weights map
 	if err != nil {
 		return err
 	}
-	defer tx.Rollback()
+	defer func() { _ = tx.Rollback() }()
 
 	stmt, err := tx.PrepareContext(ctx, `
 		INSERT INTO concept_weights (concept, weight, updated_at)

internal/db/sqlite/session_test.go

@@ -211,8 +211,8 @@ func (s *SessionStoreSuite) TestFindAnySDKSession_Scenarios() {
 	tests := []struct {
 		name            string
 		claudeSessionID string
-		wantFound       bool
 		wantProject     string
+		wantFound       bool
 	}{
 		{
 			name:            "find existing session 1",

internal/db/sqlite/store.go

@@ -94,8 +94,8 @@ func (s *Store) GetStmt(query string) (*sql.Stmt, error) {
 	defer s.stmtMu.Unlock()
 
 	// Double-check after acquiring write lock
-	if stmt, ok := s.stmtCache[query]; ok {
-		return stmt, nil
+	if cachedStmt, ok := s.stmtCache[query]; ok {
+		return cachedStmt, nil
 	}
 
 	stmt, err := s.db.Prepare(query)

internal/db/sqlite/store_test.go

@@ -130,13 +130,13 @@ func (s *StoreSuite) TestQueryContext() {
 	seedSession(s.T(), s.db, "claude-1", "sdk-1", "project-a")
 
 	tests := []struct {
+		setupFunc  func()
+		assertFunc func(rows *sql.Rows)
 		name       string
 		query      string
 		args       []interface{}
-		wantErr    bool
 		wantRows   int
-		setupFunc  func()
-		assertFunc func(rows *sql.Rows)
+		wantErr    bool
 	}{
 		{
 			name:     "query existing session",
@@ -366,8 +366,8 @@ func (s *HelpersSuite) TestNullInt() {
 func (s *HelpersSuite) TestRepeatPlaceholders() {
 	tests := []struct {
 		name     string
-		input    int
 		expected string
+		input    int
 	}{
 		{
 			name:     "zero",
@@ -438,10 +438,10 @@ func TestBuildGetByIDsQuery(t *testing.T) {
 	tests := []struct {
 		name      string
 		baseQuery string
-		ids       []int64
 		orderBy   string
-		limit     int
 		wantQuery string
+		ids       []int64
+		limit     int
 		wantArgs  int
 	}{
 		{
@@ -483,10 +483,10 @@ func TestEnsureSessionExists(t *testing.T) {
 	ctx := context.Background()
 
 	tests := []struct {
+		setup        func()
 		name         string
 		sdkSessionID string
 		project      string
-		setup        func()
 		wantErr      bool
 	}{
 		{