Get the repo ready for F-Droid

- License: AGPL-3.0-or-later (LICENSE, every package.json, README).
- MUSICSHARE_FOSS=1 builds leave out the only closed-source code, Google's
  ML Kit / Play Services barcode scanner bundled by expo-camera; the scan
  screen then decodes small camera snapshots with jsQR instead.
- Expo modules build from source rather than from precompiled AARs, as
  F-Droid requires (that's also what makes the scanner switch take effect).
  Verified: a FOSS build contains no ML Kit or Play Services classes.
- Release builds default to the production server, and come out unsigned
  without our upload key (F-Droid signs with its own). versionCode 1.
- Store listing in fastlane/metadata/android, a draft fdroiddata recipe in
  fdroid/, and docs/FDROID.md with the submission steps.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MzFywujuH9TiuXbr9vjoX8

apps/mobile/app.config.ts

@@ -10,11 +10,17 @@ import type { ConfigContext, ExpoConfig } from 'expo/config';
 export default ({ config }: ConfigContext): ExpoConfig => {
   const apiUrl = process.env.EXPO_PUBLIC_API_URL ?? '';
   const localHttp = apiUrl.startsWith('http://');
+  // F-Droid (MUSICSHARE_FOSS=1): no closed-source libraries. The only one is the Google ML Kit /
+  // Play Services barcode scanner expo-camera bundles; the scan screen decodes QR codes in JS instead.
+  const foss = process.env.MUSICSHARE_FOSS === '1';
+  type Plugin = NonNullable<ExpoConfig['plugins']>[number];
+  const plugins = (config.plugins ?? []).map(
+    (plugin): Plugin =>
+      foss && Array.isArray(plugin) && plugin[0] === 'expo-camera' ? ['expo-camera', { ...plugin[1], barcodeScannerEnabled: false }] : plugin,
+  );
   return {
     ...(config as ExpoConfig),
-    plugins: [
-      ...(config.plugins ?? []),
-      ['expo-build-properties', { android: { usesCleartextTraffic: localHttp } }],
-    ],
+    extra: { ...config.extra, foss },
+    plugins: [...plugins, ['expo-build-properties', { android: { usesCleartextTraffic: localHttp } }] satisfies Plugin],
   };
 };