Isolate extension WebView profiles and follow host proxy settings

ui/flutter/third_party/README.md

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+# Native WebView host bridge
+
+Vendored unmodified Dart facades and native sources from pub.dev:
+
+- flutter_inappwebview_macos 1.1.2
+- flutter_inappwebview_ios 1.1.2
+- flutter_inappwebview_android 1.1.3
+
+Each package retains its upstream license. Versions and original archive hashes
+are available in the parent commit's pubspec.lock.
+
+Local native changes are limited to:
+
+- `GopeedProfiles`: prepare a persistent profile and apply the internal loopback
+  proxy before creating a WebView. Apple uses SOCKS5 to cover HTTP as well as HTTPS;
+  Android uses the application-wide HTTP proxy override completion callback.
+- `InAppWebViewSettings` and `InAppWebView`: read the host-only `gopeedProfileId`
+  setting and attach the profile before navigation.
+- `MyCookieManager`: route cookie operations to the requested profile, capturing
+  the store per operation so asynchronous calls cannot cross profiles.
+
+`lib/app/rpc/webview_profile.dart` uses the existing plugin method channel and
+serializes these internal settings. No extension JavaScript API is added.
+
+Apple requires macOS 14 / iOS 17 for named persistent stores and proxy settings.
+Android requires `MULTI_PROFILE` and `PROXY_OVERRIDE`; unsupported runtimes return
+an explicit unavailable error rather than opening a shared, unproxied browser.
+
+When updating upstream, refresh these three packages, reapply the above changes,
+and run `tool/webview_profile_check.dart` on a native Apple host. Do not patch the
+user's pub cache: dependency_overrides selects these tracked sources reproducibly.