Switch remote deploy to vendored source builds

Move remote deployment to a vendored source bundle built on the target host via Docker so redeploys no longer require local cross-compilation or host Go installation.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

vendor/github.com/wailsapp/go-webview2/webviewloader/README.md

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+# Webviewloader
+
+Webviewloader is a port of [OpenWebView2Loader](https://github.com/jchv/OpenWebView2Loader) to Go.
+
+It is intended to be feature-complete with the original WebView2Loader distributed with
+the WebView2 NuGet package, but some features are intentionally not implemented.
+
+## Status
+
+- [x] CompareBrowserVersions
+- [x] CreateCoreWebView2Environment
+- [x] CreateCoreWebView2EnvironmentWithOptions
+- [x] GetAvailableCoreWebView2BrowserVersionString
+
+## Not implemented features
+
+- Registry Overrides of Parameters
+- Env Variable Overrides of Parameters
+- Does not incorporate `GetCurrentPackageInfo` to search for an installed runtime