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/detect-libc/lib/elf.js

@@ -0,0 +1,39 @@
+// Copyright 2017 Lovell Fuller and others.
+// SPDX-License-Identifier: Apache-2.0
+
+'use strict';
+
+const interpreterPath = (elf) => {
+  if (elf.length < 64) {
+    return null;
+  }
+  if (elf.readUInt32BE(0) !== 0x7F454C46) {
+    // Unexpected magic bytes
+    return null;
+  }
+  if (elf.readUInt8(4) !== 2) {
+    // Not a 64-bit ELF
+    return null;
+  }
+  if (elf.readUInt8(5) !== 1) {
+    // Not little-endian
+    return null;
+  }
+  const offset = elf.readUInt32LE(32);
+  const size = elf.readUInt16LE(54);
+  const count = elf.readUInt16LE(56);
+  for (let i = 0; i < count; i++) {
+    const headerOffset = offset + (i * size);
+    const type = elf.readUInt32LE(headerOffset);
+    if (type === 3) {
+      const fileOffset = elf.readUInt32LE(headerOffset + 8);
+      const fileSize = elf.readUInt32LE(headerOffset + 32);
+      return elf.subarray(fileOffset, fileOffset + fileSize).toString().replace(/\0.*$/g, '');
+    }
+  }
+  return null;
+};
+
+module.exports = {
+  interpreterPath
+};