接入移动端原生扫码能力

新增 scanner.scanQrCode HostBridge 契约与二维码结果归一。

接入 Expo Camera 扫码 overlay 并保留 H5 浏览器扫码回退。

让 Tauri 白名单识别扫码 method 但不声明桌面扫码能力。

同步原生壳门禁、Expo 权限检查、方案文档和共享决策记录。

apps/desktop-shell/src-tauri/src/host_bridge/dispatch.rs

@@ -636,7 +636,7 @@ mod tests {
 
     #[test]
     fn unsupported_method_is_explicit() {
-        for method in ["auth.requestLogin", "payment.request"] {
+        for method in ["auth.requestLogin", "payment.request", "scanner.scanQrCode"] {
             let response = resolve_host_bridge_request(request(method));
 
             assert!(!response.ok);

apps/desktop-shell/src-tauri/src/host_bridge/protocol.rs

@@ -5,7 +5,7 @@ use std::sync::{Arc, Condvar, Mutex};
 
 pub(crate) const HOST_BRIDGE_PROTOCOL: &str = "GenarrativeHostBridge";
 pub(crate) const HOST_BRIDGE_VERSION: u8 = 1;
-pub(crate) const HOST_BRIDGE_METHODS: [&str; 23] = [
+pub(crate) const HOST_BRIDGE_METHODS: [&str; 24] = [
     "host.getRuntime",
     "appearance.getColorScheme",
     "auth.requestLogin",
@@ -25,6 +25,7 @@ pub(crate) const HOST_BRIDGE_METHODS: [&str; 23] = [
     "file.exportImage",
     "file.importImage",
     "file.captureImage",
+    "scanner.scanQrCode",
     "file.importAudio",
     "file.exportAudio",
     "haptics.impact",