feat(flutter,macos,ios): scaffold platform Xcode projects via flutter create

Ran `flutter create --platforms=macos,ios --project-name=chanora_flutter
--org=app.chanora .` on the M1 Mac to generate the standard Flutter
platform-specific scaffolding (Runner.xcodeproj, Podfile, AppDelegate,
entitlements, etc.) for both macOS and iOS.

The cross-platform Dart source (lib/) and Rust workspace (crates/,
core/) carry the actual application logic; these scaffolds are
required only so flutter build macos / ios can resolve their Xcode
projects. No application code added.

macOS smoke-launch from the M1 Mac verified the bridge dylib load
path: after manually wrapping libchanora_bridge.dylib into a proper
chanora_bridge.framework bundle (FRB on macOS expects a framework,
not a plain dylib) and codesigning ad-hoc, the runner starts cleanly
through 'bridge initialised', 'identity store initialised', 'bookmark
store initialised' just like the Linux runner.

Following commits will:
  * Wire the framework-bundling step into build glue (currently manual
    install_name_tool + codesign).
  * Replace the macOS PTT backend stub (crates/chanora_audio/src/
    ptt_backends/macos.rs) with live IOHIDCheckAccess +
    CGEventTapCreate so the descriptor advertises real L2/L3 capability
    on a permission-granted box (SDD-085).
  * Add the iOS AVAudioSession PlayAndRecord+voiceChat wiring.
  * Add docs/verification/macos-p0-acceptance.md and ios-p0-acceptance.md.

apps/chanora_flutter/.metadata

@@ -5,7 +5,7 @@
 
 version:
   revision: "00b0c91f06209d9e4a41f71b7a512d6eb3b9c694"
-  channel: "stable"
+  channel: "[user-branch]"
 
 project_type: app
 
@@ -15,10 +15,10 @@ migration:
     - platform: root
       create_revision: 00b0c91f06209d9e4a41f71b7a512d6eb3b9c694
       base_revision: 00b0c91f06209d9e4a41f71b7a512d6eb3b9c694
-    - platform: android
+    - platform: ios
       create_revision: 00b0c91f06209d9e4a41f71b7a512d6eb3b9c694
       base_revision: 00b0c91f06209d9e4a41f71b7a512d6eb3b9c694
-    - platform: linux
+    - platform: macos
       create_revision: 00b0c91f06209d9e4a41f71b7a512d6eb3b9c694
       base_revision: 00b0c91f06209d9e4a41f71b7a512d6eb3b9c694