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/lightningcss/node/index.js

@@ -0,0 +1,28 @@
+let parts = [process.platform, process.arch];
+if (process.platform === 'linux') {
+  const { MUSL, familySync } = require('detect-libc');
+  const family = familySync();
+  if (family === MUSL) {
+    parts.push('musl');
+  } else if (process.arch === 'arm') {
+    parts.push('gnueabihf');
+  } else {
+    parts.push('gnu');
+  }
+} else if (process.platform === 'win32') {
+  parts.push('msvc');
+}
+
+if (process.env.CSS_TRANSFORMER_WASM) {
+  module.exports = require(`../pkg`);
+} else {
+  try {
+    module.exports = require(`lightningcss-${parts.join('-')}`);
+  } catch (err) {
+    module.exports = require(`../lightningcss.${parts.join('-')}.node`);
+  }
+}
+
+module.exports.browserslistToTargets = require('./browserslistToTargets');
+module.exports.composeVisitors = require('./composeVisitors');
+module.exports.Features = require('./flags').Features;