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/shared/clients/__init__.py

@@ -0,0 +1,20 @@
+"""
+API Clients for Core-API
+
+Provides HTTP/WebSocket clients for external infrastructure services.
+"""
+from src.shared.clients.portainer_client import PortainerClient, get_portainer_client
+from src.shared.clients.npm_client import NPMClient, get_npm_client
+from src.shared.clients.homeassistant_client import HomeAssistantClient, get_homeassistant_client
+from src.shared.clients.authentik_client import AuthentikClient, get_authentik_client
+
+__all__ = [
+    "PortainerClient",
+    "get_portainer_client",
+    "NPMClient",
+    "get_npm_client",
+    "HomeAssistantClient",
+    "get_homeassistant_client",
+    "AuthentikClient",
+    "get_authentik_client",
+]