fix(lint): auto-fix ruff violations and tune lint rules

- Auto-fixed 4,496 lint issues (import sorting, modern syntax, etc.)
- Added ignore rules for patterns intentional in this codebase:
  E402 (late imports), E712 (SQLAlchemy filters), B904 (raise from),
  SIM108/SIM105/SIM117 (readability preferences)
- Added per-file ignores for tests and scripts
- Excluded broken scripts/rename_terminology.py (has curly quotes)

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

app/api/main.py

@@ -10,7 +10,7 @@ This module provides:
 
 from fastapi import APIRouter
 
-from app.api.v1 import admin, merchant, platform, storefront, store, webhooks
+from app.api.v1 import admin, merchant, platform, store, storefront, webhooks
 
 api_router = APIRouter()