feat(partner): detect and resync partner mismatches on already-imported orders

Detects PF↔PJ transitions and CUI changes after import; auto-resyncs
uninvoiced orders (max 5/cycle) and shows visual alert for invoiced ones.
- SQLite: partner_mismatch column + batch helpers
- sync_service: detection loop + _resync_partner_for_order
- dashboard: red dot + attention card indicator
- modal: alert with contextual message and resync button

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

api/app/database.py

@@ -353,6 +353,7 @@ def init_sqlite():
             ("anaf_denumire_mismatch", "INTEGER DEFAULT 0"),
             ("denumire_anaf", "TEXT"),
             ("address_mismatch", "INTEGER DEFAULT 0"),
+            ("partner_mismatch", "INTEGER DEFAULT 0"),
         ]:
             if col not in order_cols:
                 conn.execute(f"ALTER TABLE orders ADD COLUMN {col} {typedef}")