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/package.json

@@ -2,6 +2,7 @@
   "name": "@musicshare/mobile",
   "main": "expo-router/entry",
   "version": "1.0.0",
+  "license": "AGPL-3.0-or-later",
   "dependencies": {
     "@expo-google-fonts/space-grotesk": "^0.4.1",
     "@expo/ui": "~57.0.21",
@@ -25,6 +26,8 @@
     "expo-symbols": "~57.0.3",
     "expo-system-ui": "~57.0.4",
     "expo-web-browser": "~57.0.3",
+    "jpeg-js": "^0.4.4",
+    "jsqr": "^1.4.0",
     "react": "19.2.3",
     "react-dom": "19.2.3",
     "react-native": "0.86.3",
@@ -52,5 +55,14 @@
     "typecheck": "tsc --noEmit",
     "lint": "expo lint"
   },
-  "private": true
+  "private": true,
+  "expo": {
+    "autolinking": {
+      "android": {
+        "buildFromSource": [
+          ".*"
+        ]
+      }
+    }
+  }
 }