06/05 Optimize app: add Plaid reset sync

app/routes/plaid.py

@@ -369,6 +369,25 @@ def refresh_liabilities_view(item_db_id):
     return redirect(url_for('plaid.index'))
 
 
+# ── Full Resync (clear cursor so next sync fetches full history) ──────────────
+
+@plaid_bp.route('/resync/<int:item_db_id>', methods=['POST'])
+@login_required
+def full_resync(item_db_id):
+    item = db.get_or_404(PlaidItem, item_db_id)
+    item.cursor = None
+    item.last_synced_at = None
+    for pa in item.accounts.filter_by(is_active=True).all():
+        pa.last_sync_date = None
+    db.session.commit()
+    flash(
+        f'{item.institution_name}: cursor reset. '
+        f'Next sync will fetch full available history — duplicates will be skipped automatically.',
+        'info'
+    )
+    return redirect(url_for('plaid.index'))
+
+
 # ── Disconnect ────────────────────────────────────────────────────────────────
 
 @plaid_bp.route('/disconnect/<int:item_db_id>', methods=['POST'])