chore(release): bump version to 2.1.6 (build 131)

Version: CURRENT_PROJECT_VERSION 130 -> 131 (project.yml, AGENTS.md, READMEs,
docs/llms.txt).

fix(flow): host-app identification now compiles in every build configuration
(Debug, TestFlight, Release). The arbiter probe and HostAppIdentity were
DEBUG-only, so TestFlight/App Store builds never knew the host bundle id and
could not auto-return after a startflow handoff. Debug-only logging and the
Home test card are unchanged.

Also includes the pending work in the tree:
- Home: single account/setup card surface (HomeAccountSurfacePolicy/Views)
- Wide screens: voice key row and centred mic placement, iPhone Duo layout
- Keyboard: clipboard skill ranking and AI skill layout updates
- Debug: account session handoff to the Simulator (+ import script)
- Docs: portfolio assets, privacy policy URL, site/README refresh

OSGKeyboardExt/Utilities/OSGHostArbiterProbe.h

@@ -1,14 +1,14 @@
 // OSGHostArbiterProbe.h
 // OSGKeyboard · Keyboard Extension
 //
-// 临时调试探针（仅 DEBUG）：iOS 26.4+ 通过 _UIKeyboardArbiterClient 回调
-// 读取宿主 App 的 bundle ID。原理参考 editorss/KeyboardHostBundleID（MIT）。
+// 宿主识别探针（Debug / TestFlight / Release 均编译）：iOS 26.4+ 通过
+// _UIKeyboardArbiterClient 回调读取宿主 App 的 bundle ID，供冷启动后自动跳回。
+// 原理参考 editorss/KeyboardHostBundleID（MIT）。
 // 必须在 +load 安装，否则可能错过键盘首次切换宿主时的回调。
+// 所有私有符号运行时按字符串查找，任何一步失败都静默退化为“识别不到宿主”。
 
 #import <Foundation/Foundation.h>
 
-#ifdef DEBUG
-
 NS_ASSUME_NONNULL_BEGIN
 
 /// 回调可能在 arbiter 的私有队列上触发，不保证主线程。
@@ -34,5 +34,3 @@ typedef void (^OSGHostArbiterCaptureHandler)(NSString *_Nullable bundleId, NSStr
 @end
 
 NS_ASSUME_NONNULL_END
-
-#endif