feat(sync): add GoMag API client with Phase 0 auto-download

- New gomag_client.py service: async httpx client that downloads orders
  from GoMag API with full pagination and 1s rate-limit sleep
- config.py: add GOMAG_API_KEY, GOMAG_API_SHOP, GOMAG_ORDER_DAYS_BACK,
  GOMAG_LIMIT, GOMAG_API_URL settings
- sync_service.py: Phase 0 downloads fresh orders before reading JSONs;
  graceful skip if API keys not configured
- start.sh: auto-detect INSTANTCLIENTPATH from .env, fallback to thin mode
- .env.example: document GoMag API variables

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

api/app/config.py

@@ -41,6 +41,13 @@ class Settings(BaseSettings):
     ID_GESTIUNE: int = 0
     ID_SECTIE: int = 0
 
+    # GoMag API
+    GOMAG_API_KEY: str = ""
+    GOMAG_API_SHOP: str = ""
+    GOMAG_ORDER_DAYS_BACK: int = 7
+    GOMAG_LIMIT: int = 100
+    GOMAG_API_URL: str = "https://api.gomag.ro/api/v1/order/read/json"
+
     @model_validator(mode="after")
     def resolve_paths(self):
         """Resolve relative paths against known roots, independent of CWD."""