feat: collapse plugin runtime to one tier behind a plugin SDK

tsconfig.plugins.json

@@ -36,7 +36,8 @@
     "plugins/automations/backend/**/*.ts",
     "plugins/network-topology/backend/**/*.ts",
     "plugins/workspaces/backend/**/*.ts",
-    "plugins/web-endpoint/backend/**/*.ts"
+    "plugins/web-endpoint/backend/**/*.ts",
+    "plugins/tailscale/backend/**/*.ts"
   ],
   "exclude": ["src/**/*.test.ts"]
 }