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/@babel/helper-globals/package.json

@@ -0,0 +1,32 @@
+{
+  "name": "@babel/helper-globals",
+  "version": "7.28.0",
+  "author": "The Babel Team (https://babel.dev/team)",
+  "license": "MIT",
+  "description": "A collection of JavaScript globals for Babel internal usage",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/babel/babel.git",
+    "directory": "packages/babel-helper-globals"
+  },
+  "publishConfig": {
+    "access": "public"
+  },
+  "exports": {
+    "./data/browser-upper.json": "./data/browser-upper.json",
+    "./data/builtin-lower.json": "./data/builtin-lower.json",
+    "./data/builtin-upper.json": "./data/builtin-upper.json",
+    "./package.json": "./package.json"
+  },
+  "keywords": [
+    "babel",
+    "globals"
+  ],
+  "devDependencies": {
+    "globals": "^16.1.0"
+  },
+  "engines": {
+    "node": ">=6.9.0"
+  },
+  "type": "commonjs"
+}