Add OpenAPI docs, frontend, migrations, and API updates

- OpenAPI: add missing endpoints (add-from-url, subscriptions, public availability)
- OpenAPI: CalendarSubscription schema, Subscriptions tag
- Frontend app
- Migrations: count_for_availability, subscriptions_sync, user_preferences, calendar_settings
- Config, rate limit, auth, calendar, booking, ICS, availability, user service updates

Made-with: Cursor

frontend/node_modules/@rolldown/pluginutils/package.json

@@ -0,0 +1,36 @@
+{
+  "name": "@rolldown/pluginutils",
+  "version": "1.0.0-beta.27",
+  "license": "MIT",
+  "type": "module",
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/rolldown/rolldown.git",
+    "directory": "packages/pluginutils"
+  },
+  "publishConfig": {
+    "access": "public"
+  },
+  "main": "./dist/index.cjs",
+  "module": "./dist/index.js",
+  "types": "./dist/index.d.ts",
+  "exports": {
+    ".": {
+      "import": "./dist/index.js",
+      "require": "./dist/index.cjs"
+    }
+  },
+  "files": [
+    "dist"
+  ],
+  "devDependencies": {
+    "@types/picomatch": "^4.0.0",
+    "picomatch": "^4.0.2",
+    "tsdown": "0.12.9",
+    "vitest": "^3.0.1"
+  },
+  "scripts": {
+    "build": "tsdown",
+    "test": "vitest --typecheck"
+  }
+}