feat: add JS-009 rule for Utils.showToast() and update naming docs

Architecture rules:
- Add JS-009: Use Utils.showToast() instead of alert() or window.showToast
- Supports inline noqa comments to suppress warnings

Documentation:
- Update naming-conventions.md to emphasize plural table names (industry standard)
- Document that plural table names follow Rails/Django/Laravel conventions

Schema:
- Add from_attributes to VendorUserResponse for ORM compatibility

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

models/schema/auth.py

@@ -153,3 +153,5 @@ class VendorUserResponse(BaseModel):
     email: str
     role: str
     is_active: bool
+
+    model_config = {"from_attributes": True}