feat: add dashboard API with quick links and widgets

- Dashboard domain with Quick Links CRUD + reorder endpoints
- Dashboard widgets management endpoints
- Database migrations for quick_links and dashboard_widgets tables
- Static file controller for Organizr widgets
- Default local user when OIDC is disabled
- Domain-based architecture refactor (src/domains/, src/shared/)
- Test suite updated for new structure (285 tests passing)

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

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

src/domains/infrastructure/__init__.py

@@ -0,0 +1,8 @@
+"""
+Infrastructure Domain
+
+Provides infrastructure management endpoints for Docker/Portainer and NPM.
+"""
+from src.domains.infrastructure.controller import infrastructure_controller
+
+__all__ = ["infrastructure_controller"]