test: add comprehensive tests for tool workshop functionality

Backend tests:
- Unit tests for docker_build service (successful/failed builds, context, paths)
- Unit tests for readiness_probe service (success, timeout, retries, edge cases)
- Integration tests for config_folders API (CRUD + project overrides)
- Integration tests for tool_types API with new fields
- Integration tests for tool_configs API with new fields

Frontend tests:
- ToolWorkshopPage component tests (all 3 tabs, create/edit/delete)
- API client tests for tool_types and config_folders

Fixes:
- Add field_validator import to tool_configs.py
- Add JSON import to tool_config model
- Update frontend test button names to match UI (Create Tool Type, Add Config, Create Folder)

Quality gates: backend unit tests passing (23/23)

apps/api/tests/integration/test_users_api.py

@@ -8,7 +8,7 @@ import pytest
 from sqlalchemy import text
 from sqlalchemy.ext.asyncio import create_async_engine
 
-from src.auth.jwt_service import mint_access_token
+from src.auth.session import mint_access_token
 from src.config import Settings, build_database_url
 from src.models import Base
 from src.models.user import User