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/auth/__init__.py

@@ -0,0 +1,48 @@
+"""
+Authentication Domain
+
+Provides OIDC/OAuth2 authentication via Authentik, user management,
+roles, groups, and API key authentication.
+"""
+from src.domains.auth.oidc import (
+    get_current_user,
+    get_admin_user,
+    get_optional_user,
+    get_forward_auth_user,
+    get_forward_auth_admin,
+    oidc_config,
+)
+from src.domains.auth.service import AuthService, get_auth_service
+from src.domains.auth.controller import auth_controller
+from src.domains.auth.models import (
+    User,
+    Role,
+    UserRole,
+    Group,
+    UserPreferences,
+    ApiKey,
+    user_groups,
+)
+
+__all__ = [
+    # OIDC dependencies
+    "get_current_user",
+    "get_admin_user",
+    "get_optional_user",
+    "get_forward_auth_user",
+    "get_forward_auth_admin",
+    "oidc_config",
+    # Service
+    "AuthService",
+    "get_auth_service",
+    # Controller
+    "auth_controller",
+    # Models
+    "User",
+    "Role",
+    "UserRole",
+    "Group",
+    "UserPreferences",
+    "ApiKey",
+    "user_groups",
+]