Flatten repo: move client/ contents to repo root

The project is no longer a monorepo/workspace - there is only a single
app package. Remove the redundant client/ nesting: all source, the
Capacitor Android project, config files and package.json/tsconfig now
live directly at the repo root.

- Merge client/package.json into root package.json (drop the
  workspaces field and the now-unnecessary bun --cwd client wrappers).
- Merge client/bun.lock (the actual dependency lockfile) into the
  root, replacing the stale workspace-only root lockfile.
- Move src/, public/, android/, index.html, vite.config.ts,
  capacitor.config.ts, tsconfig.{app,node}.json to the repo root.
- Update Dockerfile.android to build from the repo root instead of
  cd'ing into client/.
- Update .github/workflows/ci.yml type-check step to run bun run build
  directly instead of bun --cwd client run build.
- Update README.md and .github/copilot-instructions.md to drop
  references to the client/ subdirectory.
- Drop the stale server/downloads/ entry from .gitignore (leftover
  from an old server-based architecture that no longer exists).

android/app/src/main/AndroidManifest.xml

@@ -0,0 +1,44 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+
+    <application
+        android:allowBackup="true"
+        android:icon="@mipmap/ic_launcher"
+        android:label="@string/app_name"
+        android:roundIcon="@mipmap/ic_launcher_round"
+        android:supportsRtl="true"
+        android:usesCleartextTraffic="true"
+        android:theme="@style/AppTheme">
+
+        <activity
+            android:configChanges="orientation|keyboardHidden|keyboard|screenSize|locale|smallestScreenSize|screenLayout|uiMode|navigation"
+            android:name=".MainActivity"
+            android:label="@string/title_activity_main"
+            android:theme="@style/AppTheme.NoActionBarLaunch"
+            android:launchMode="singleTask"
+            android:exported="true">
+
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+
+        </activity>
+
+        <provider
+            android:name="androidx.core.content.FileProvider"
+            android:authorities="${applicationId}.fileprovider"
+            android:exported="false"
+            android:grantUriPermissions="true">
+            <meta-data
+                android:name="android.support.FILE_PROVIDER_PATHS"
+                android:resource="@xml/file_paths"></meta-data>
+        </provider>
+    </application>
+
+    <!-- Permissions -->
+
+    <uses-permission android:name="android.permission.INTERNET" />
+    <uses-permission android:name="android.permission.CAMERA" />
+    <uses-feature android:name="android.hardware.usb.host" android:required="false"/>
+</manifest>