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/article_summary_repo.go

@@ -0,0 +1,97 @@
+package db
+
+import (
+	"context"
+	"crypto/sha256"
+	"database/sql"
+	"encoding/hex"
+	"encoding/json"
+	"strings"
+	"time"
+)
+
+type ArticleSummary struct {
+	ID        int64     `json:"id"`
+	URLHash   string    `json:"urlHash"`
+	URL       string    `json:"url"`
+	Events    []string  `json:"events"`
+	CreatedAt time.Time `json:"createdAt"`
+	ExpiresAt time.Time `json:"expiresAt"`
+}
+
+type ArticleSummaryRepository struct {
+	db *PostgresDB
+}
+
+func NewArticleSummaryRepository(db *PostgresDB) *ArticleSummaryRepository {
+	return &ArticleSummaryRepository{db: db}
+}
+
+func (r *ArticleSummaryRepository) hashURL(url string) string {
+	normalized := strings.TrimSpace(url)
+	normalized = strings.TrimSuffix(normalized, "/")
+	normalized = strings.TrimPrefix(normalized, "https://")
+	normalized = strings.TrimPrefix(normalized, "http://")
+	normalized = strings.TrimPrefix(normalized, "www.")
+
+	hash := sha256.Sum256([]byte(normalized))
+	return hex.EncodeToString(hash[:])
+}
+
+func (r *ArticleSummaryRepository) GetByURL(ctx context.Context, url string) (*ArticleSummary, error) {
+	urlHash := r.hashURL(url)
+
+	query := `
+		SELECT id, url_hash, url, events, created_at, expires_at
+		FROM article_summaries 
+		WHERE url_hash = $1 AND expires_at > NOW()
+	`
+
+	var a ArticleSummary
+	var eventsJSON []byte
+
+	err := r.db.db.QueryRowContext(ctx, query, urlHash).Scan(
+		&a.ID, &a.URLHash, &a.URL, &eventsJSON, &a.CreatedAt, &a.ExpiresAt,
+	)
+	if err == sql.ErrNoRows {
+		return nil, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	json.Unmarshal(eventsJSON, &a.Events)
+	return &a, nil
+}
+
+func (r *ArticleSummaryRepository) Save(ctx context.Context, url string, events []string, ttl time.Duration) error {
+	urlHash := r.hashURL(url)
+	eventsJSON, _ := json.Marshal(events)
+	expiresAt := time.Now().Add(ttl)
+
+	query := `
+		INSERT INTO article_summaries (url_hash, url, events, expires_at)
+		VALUES ($1, $2, $3, $4)
+		ON CONFLICT (url_hash) 
+		DO UPDATE SET 
+			events = EXCLUDED.events,
+			expires_at = EXCLUDED.expires_at
+	`
+
+	_, err := r.db.db.ExecContext(ctx, query, urlHash, url, eventsJSON, expiresAt)
+	return err
+}
+
+func (r *ArticleSummaryRepository) Delete(ctx context.Context, url string) error {
+	urlHash := r.hashURL(url)
+	_, err := r.db.db.ExecContext(ctx, "DELETE FROM article_summaries WHERE url_hash = $1", urlHash)
+	return err
+}
+
+func (r *ArticleSummaryRepository) CleanupExpired(ctx context.Context) (int64, error) {
+	result, err := r.db.db.ExecContext(ctx, "DELETE FROM article_summaries WHERE expires_at < NOW()")
+	if err != nil {
+		return 0, err
+	}
+	return result.RowsAffected()
+}