feat(PROJ-13,PROJ-42): REST API v1 + Gespeicherte Suchanfragen

PROJ-13: Externe REST API für CRM/ERP-Anbindung
- API-Key Middleware mit SHA-256-Hash-Lookup + Token-Bucket Rate-Limiter
- GET /api/v1/mails — Suche mit Paginierung (max 100/Seite)
- GET /api/v1/mails/{id} — Mail-Metadaten als JSON
- GET /api/v1/mails/{id}/raw — Original-EML Download
- Admin-Endpoints: POST/GET/DELETE /api/admin/apikeys
- Tenant-Isolation, Audit-Log, 405 für non-GET Methoden

PROJ-42: Gespeicherte Suchanfragen
- Tabelle saved_searches (user_id, tenant_id, name, query_json)
- GET/POST/DELETE /api/searches/saved mit Ownership-Check
- Frontend: "Suche speichern"-Button + Popover mit gespeicherten Suchen
- shadcn/ui Komponenten, Loading/Empty States

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/storage/storage.go

@@ -274,6 +274,40 @@ func (s *Store) initSchema(ctx context.Context) error {
 		ALTER TABLE emails ADD COLUMN IF NOT EXISTS in_reply_to TEXT;
 		CREATE INDEX IF NOT EXISTS idx_emails_thread ON emails (thread_id);
 	`)
+	if err != nil {
+		return err
+	}
+	// PROJ-13: API keys for external CRM integration
+	_, err = s.db.Exec(ctx, `
+		CREATE TABLE IF NOT EXISTS api_keys (
+			id           BIGSERIAL PRIMARY KEY,
+			tenant_id    BIGINT NOT NULL,
+			name         TEXT NOT NULL,
+			token_hash   TEXT NOT NULL UNIQUE,
+			role         TEXT NOT NULL DEFAULT 'user',
+			active       BOOLEAN NOT NULL DEFAULT TRUE,
+			rate_limit   INT NOT NULL DEFAULT 60,
+			created_at   TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+			last_used_at TIMESTAMPTZ
+		);
+		CREATE INDEX IF NOT EXISTS idx_api_keys_token_hash ON api_keys(token_hash);
+	`)
+	if err != nil {
+		return err
+	}
+
+	// PROJ-42: Gespeicherte Suchanfragen
+	_, err = s.db.Exec(ctx, `
+		CREATE TABLE IF NOT EXISTS saved_searches (
+			id         BIGSERIAL PRIMARY KEY,
+			user_id    BIGINT NOT NULL,
+			tenant_id  BIGINT NOT NULL,
+			name       TEXT NOT NULL,
+			query_json JSONB NOT NULL,
+			created_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+		);
+		CREATE INDEX IF NOT EXISTS idx_saved_searches_user ON saved_searches(user_id, tenant_id);
+	`)
 	return err
 }
 
@@ -1295,3 +1329,25 @@ func (s *Store) DBQueryRow(ctx context.Context, sql string, args ...interface{})
 type noopRow struct{}
 
 func (n *noopRow) Scan(dest ...interface{}) error { return nil }
+
+// DBExec exposes a single DB exec for use by API handlers (e.g., API key management).
+// Returns the number of rows affected. Returns 0 if no DB is configured.
+func (s *Store) DBExec(ctx context.Context, sql string, args ...interface{}) (int64, error) {
+	if s.db == nil {
+		return 0, nil
+	}
+	tag, err := s.db.Exec(ctx, sql, args...)
+	if err != nil {
+		return 0, err
+	}
+	return tag.RowsAffected(), nil
+}
+
+// DBQuery exposes a multi-row DB query for use by API handlers (e.g., API key listing).
+// Returns nil rows if no DB is configured.
+func (s *Store) DBQuery(ctx context.Context, sql string, args ...interface{}) (pgx.Rows, error) {
+	if s.db == nil {
+		return nil, fmt.Errorf("storage: no database configured")
+	}
+	return s.db.Query(ctx, sql, args...)
+}