feat: Go backend, enhanced search, new widgets, Docker deploy

Major changes:
- Add Go backend (backend/) with microservices architecture
- Enhanced master-agents-svc: reranker, content-classifier, stealth-crawler,
  proxy-manager, media-search, fastClassifier, language detection
- New web-svc widgets: KnowledgeCard, ProductCard, ProfileCard, VideoCard,
  UnifiedCard, CardGallery, InlineImageGallery, SourcesPanel, RelatedQuestions
- Improved discover-svc with discover-db integration
- Docker deployment improvements (Caddyfile, vendor.sh, BUILD.md)
- Library-svc: project_id schema migration
- Remove deprecated finance-svc and travel-svc
- Localization improvements across services

Made-with: Cursor

backend/internal/db/file_repo.go

@@ -0,0 +1,149 @@
+package db
+
+import (
+	"context"
+	"database/sql"
+	"encoding/json"
+	"time"
+)
+
+type UploadedFile struct {
+	ID            string                 `json:"id"`
+	UserID        string                 `json:"userId"`
+	Filename      string                 `json:"filename"`
+	FileType      string                 `json:"fileType"`
+	FileSize      int64                  `json:"fileSize"`
+	StoragePath   string                 `json:"storagePath"`
+	ExtractedText string                 `json:"extractedText,omitempty"`
+	Metadata      map[string]interface{} `json:"metadata"`
+	CreatedAt     time.Time              `json:"createdAt"`
+}
+
+type FileRepository struct {
+	db *PostgresDB
+}
+
+func NewFileRepository(db *PostgresDB) *FileRepository {
+	return &FileRepository{db: db}
+}
+
+func (r *FileRepository) Create(ctx context.Context, f *UploadedFile) error {
+	metadataJSON, _ := json.Marshal(f.Metadata)
+
+	query := `
+		INSERT INTO uploaded_files (user_id, filename, file_type, file_size, storage_path, extracted_text, metadata)
+		VALUES ($1, $2, $3, $4, $5, $6, $7)
+		RETURNING id, created_at
+	`
+	return r.db.db.QueryRowContext(ctx, query,
+		f.UserID, f.Filename, f.FileType, f.FileSize, f.StoragePath, f.ExtractedText, metadataJSON,
+	).Scan(&f.ID, &f.CreatedAt)
+}
+
+func (r *FileRepository) GetByID(ctx context.Context, id string) (*UploadedFile, error) {
+	query := `
+		SELECT id, user_id, filename, file_type, file_size, storage_path, extracted_text, metadata, created_at
+		FROM uploaded_files 
+		WHERE id = $1
+	`
+
+	var f UploadedFile
+	var metadataJSON []byte
+
+	err := r.db.db.QueryRowContext(ctx, query, id).Scan(
+		&f.ID, &f.UserID, &f.Filename, &f.FileType, &f.FileSize,
+		&f.StoragePath, &f.ExtractedText, &metadataJSON, &f.CreatedAt,
+	)
+	if err == sql.ErrNoRows {
+		return nil, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	json.Unmarshal(metadataJSON, &f.Metadata)
+	return &f, nil
+}
+
+func (r *FileRepository) GetByUserID(ctx context.Context, userID string, limit, offset int) ([]*UploadedFile, error) {
+	query := `
+		SELECT id, user_id, filename, file_type, file_size, storage_path, extracted_text, metadata, created_at
+		FROM uploaded_files 
+		WHERE user_id = $1
+		ORDER BY created_at DESC
+		LIMIT $2 OFFSET $3
+	`
+
+	rows, err := r.db.db.QueryContext(ctx, query, userID, limit, offset)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var files []*UploadedFile
+	for rows.Next() {
+		var f UploadedFile
+		var metadataJSON []byte
+
+		if err := rows.Scan(
+			&f.ID, &f.UserID, &f.Filename, &f.FileType, &f.FileSize,
+			&f.StoragePath, &f.ExtractedText, &metadataJSON, &f.CreatedAt,
+		); err != nil {
+			return nil, err
+		}
+
+		json.Unmarshal(metadataJSON, &f.Metadata)
+		files = append(files, &f)
+	}
+
+	return files, nil
+}
+
+func (r *FileRepository) UpdateExtractedText(ctx context.Context, id, text string) error {
+	_, err := r.db.db.ExecContext(ctx,
+		"UPDATE uploaded_files SET extracted_text = $2 WHERE id = $1",
+		id, text,
+	)
+	return err
+}
+
+func (r *FileRepository) Delete(ctx context.Context, id string) error {
+	_, err := r.db.db.ExecContext(ctx, "DELETE FROM uploaded_files WHERE id = $1", id)
+	return err
+}
+
+func (r *FileRepository) GetByIDs(ctx context.Context, ids []string) ([]*UploadedFile, error) {
+	if len(ids) == 0 {
+		return nil, nil
+	}
+
+	query := `
+		SELECT id, user_id, filename, file_type, file_size, storage_path, extracted_text, metadata, created_at
+		FROM uploaded_files 
+		WHERE id = ANY($1)
+	`
+
+	rows, err := r.db.db.QueryContext(ctx, query, ids)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var files []*UploadedFile
+	for rows.Next() {
+		var f UploadedFile
+		var metadataJSON []byte
+
+		if err := rows.Scan(
+			&f.ID, &f.UserID, &f.Filename, &f.FileType, &f.FileSize,
+			&f.StoragePath, &f.ExtractedText, &metadataJSON, &f.CreatedAt,
+		); err != nil {
+			return nil, err
+		}
+
+		json.Unmarshal(metadataJSON, &f.Metadata)
+		files = append(files, &f)
+	}
+
+	return files, nil
+}