Add project scaffolding and documentation

Add .env.example with configuration for database, Redis, security, SMTP, workers, and plugins. Add .gitignore for Python, Node.js, Next.js, Docker volumes, and IDE files. Add MIT License. Update README.md with feature overview, quick start guide, architecture description, plugin system documentation, security details, backup/restore instructions, and developer setup. Add Alembic configuration files and placeholder directories for API, web, worker, and plugin components

apps/api/tests/test_plugin_sdk.py

@@ -0,0 +1,21 @@
+import pytest
+from apps.api.src.plugins import registry
+from apps.api.src.plugins.connectors.proxmox_ve import ProxmoxVEConnector
+from apps.api.src.plugins.connectors.adguard_home import AdGuardHomeConnector
+from apps.api.src.plugins.connectors.generic_http import GenericHTTPConnector
+
+
+def test_builtin_connectors_registered():
+    assert "proxmox-ve" in registry.list_connectors()
+    assert "adguard-home" in registry.list_connectors()
+    assert "generic-http" in registry.list_connectors()
+
+
+def test_connector_classes():
+    assert registry.get_connector("proxmox-ve") is ProxmoxVEConnector
+    assert registry.get_connector("adguard-home") is AdGuardHomeConnector
+    assert registry.get_connector("generic-http") is GenericHTTPConnector
+
+
+def test_registry_missing():
+    assert registry.get_connector("unknown") is None