0.5.22 Windows: webview points at build-runner path -> ERR_FILE_NOT_FOUND on launch

**Version:** Buzz desktop 0.5.22 (`Buzz_0.5.22_x64-setup_alpha-unsigned.exe`, also via in-app update from 0.5.20)
**OS:** Windows 11 x64, WebView2 runtime current

**Symptom:** on launch the window shows the WebView2 "File not found / ERR_FILE_NOT_FOUND" page instead of the app.

**Observed:** with `WEBVIEW2_ADDITIONAL_BROWSER_ARGUMENTS=--remote-debugging-port=9223`, `GET /json` reports the page URL as
`file:///C:/Users/RUNNER~1/AppData/Local/Temp/buzz-tauri-package-assets-izi1rV/dist` — a path on the CI build runner, not on the user's machine.

**Repro:** clean install of 0.5.22 (kill app, run installer `/S`, relaunch) reproduces every time.

**Workaround:** roll back to 0.5.20 — the same check then reports `http://tauri.localhost/` and the app loads normally, workspace and agents intact.

**Suggested cause:** the packaged frontend asset path is not being rewritten at bundle time for the Windows target, so the webview navigates to the runner's temp `dist` directory.

Reproduce the clean Windows 0.5.22 install and inspect how the packaged frontend asset path is handled for the Windows target. Compare the WebView2 URL with 0.5.20, where it is http://tauri.localhost/. Done means a clean 0.5.22 install launches the app normally without ERR_FILE_NOT_FOUND and preserves the reported workspace and agents.

Written by the indexing model from the issue text.