feat: modern macOS window chrome + Linux build script

macOS:
- Transparent title bar with hidden title, full-size content view
- macOS: inline Row header (no AppBar) with 56px traffic-light pad
- Other platforms: standard Material AppBar unchanged
- App name 'Chanora' in CFBundleName/CFBundleDisplayName (iOS + macOS)
- NSLocalNetworkUsageDescription added to both platforms

Linux:
- tools/build-linux.sh: builds Rust .so + Flutter bundle + tarball
- Verifies GTK3, libopus dev headers, Rust target
- Copies libchanora_bridge.so into bundle/lib/

apps/chanora_flutter/ios/Runner/Info.plist

@@ -7,7 +7,7 @@
 	<key>CFBundleDevelopmentRegion</key>
 	<string>$(DEVELOPMENT_LANGUAGE)</string>
 	<key>CFBundleDisplayName</key>
-	<string>Chanora Flutter</string>
+	<string>Chanora</string>
 	<key>CFBundleExecutable</key>
 	<string>$(EXECUTABLE_NAME)</string>
 	<key>CFBundleIdentifier</key>
@@ -15,7 +15,7 @@
 	<key>CFBundleInfoDictionaryVersion</key>
 	<string>6.0</string>
 	<key>CFBundleName</key>
-	<string>chanora_flutter</string>
+	<string>Chanora</string>
 	<key>CFBundlePackageType</key>
 	<string>APPL</string>
 	<key>CFBundleShortVersionString</key>