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/jiti/lib/jiti-cli.mjs

@@ -0,0 +1,34 @@
+#!/usr/bin/env node
+
+import { resolve } from "node:path";
+import nodeModule from "node:module";
+
+const script = process.argv.splice(2, 1)[0];
+
+if (!script) {
+  console.error("Usage: jiti <path> [...arguments]");
+  process.exit(1);
+}
+
+// https://nodejs.org/api/module.html#moduleenablecompilecachecachedir
+// https://github.com/nodejs/node/pull/54501
+if (nodeModule.enableCompileCache && !process.env.NODE_DISABLE_COMPILE_CACHE) {
+  try {
+    nodeModule.enableCompileCache();
+  } catch {
+    // Ignore errors
+  }
+}
+
+const pwd = process.cwd();
+
+const { createJiti } = await import("./jiti.cjs");
+
+const jiti = createJiti(pwd);
+
+const resolved = (process.argv[1] = jiti.resolve(resolve(pwd, script)));
+
+await jiti.import(resolved).catch((error) => {
+  console.error(error);
+  process.exit(1);
+});