feat: VK OAuth flow, catalog sync improvements, and expanded test suite

- Add VK OAuth implicit flow: /vk-auth redirect, /vk-callback JS page,
  /vk-callback/save endpoint with state validation
- Add VK_CLIENT_ID/VK_CLIENT_SECRET to config
- Add refresh_token/token_expires_at columns to vk_connections (migration 0006)
- Fix vk_catalog task: handle price/thumb_photo as string or dict (VK API v5.199)
- Fix connections/vk/test: use groups.getById instead of market.getAlbums
  (works with both user and group tokens)
- Add orphan deletion to mirror_to_vk: VK products not in Evotor are removed
- Handle ungrouped Evotor products: push to "Без категории" VK album
- Respect SyncConfig.is_enabled in mirror_to_vk
- Add product count column to catalog groups page
- Add group name column to catalog products page
- Expand test suite: 73 new tests covering connections routes, catalog routes,
  vk_sync task logic, and catalog task helpers (138 total, all passing)

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

web/tasks/celery_app.py

@@ -17,21 +17,45 @@ celery_app.conf.update(
     broker_connection_retry_on_startup=True,
     task_routes={
         "web.tasks.sync.*": {"queue": "sync"},
+        "web.tasks.vk_sync.*": {"queue": "sync"},
         "web.tasks.health.*": {"queue": "health"},
         "web.tasks.catalog.*": {"queue": "default"},
+        "web.tasks.vk_catalog.*": {"queue": "default"},
         "web.notifications.tasks.*": {"queue": "notifications"},
     },
     beat_schedule={
-        "refresh-catalog": {
-            "task": "web.tasks.catalog.refresh_catalog",
-            "schedule": timedelta(seconds=settings.CATALOG_REFRESH_INTERVAL_SECONDS),
-        },
-        "refresh-vk-catalog": {
-            "task": "web.tasks.vk_catalog.refresh_vk_catalog",
+        # Chain: fetch Evotor → fetch VK catalog → mirror Evotor→VK
+        # Beat fires the launcher task which chains all three sequentially.
+        "sync-pipeline": {
+            "task": "web.tasks.celery_app.run_sync_pipeline",
             "schedule": timedelta(seconds=settings.CATALOG_REFRESH_INTERVAL_SECONDS),
         },
     },
 )
 
 # Register task modules so beat/worker can discover them
-celery_app.autodiscover_tasks(["web.tasks.catalog", "web.tasks.vk_catalog"])
+celery_app.autodiscover_tasks([
+    "web.tasks.catalog",
+    "web.tasks.vk_catalog",
+    "web.tasks.vk_sync",
+    "web.tasks.celery_app",
+])
+
+
+@celery_app.task(name="web.tasks.celery_app.run_sync_pipeline", queue="default")
+def run_sync_pipeline() -> str:
+    """
+    Beat entry point. Chains refresh_catalog → refresh_vk_catalog → mirror_to_vk
+    so that mirror only runs after both catalog fetches are complete.
+    """
+    from celery import chain
+    from web.tasks.catalog import refresh_catalog
+    from web.tasks.vk_catalog import refresh_vk_catalog
+    from web.tasks.vk_sync import mirror_to_vk
+
+    chain(
+        refresh_catalog.si(),
+        refresh_vk_catalog.si(),
+        mirror_to_vk.si(),
+    ).apply_async()
+    return "pipeline dispatched"