…A entry

Move the original relay server homepage to a standalone file under
static/homepage/ and replace index.html with a minimal SPA entry
that loads bundled JS/CSS assets.

Made-with: Cursor

…erception

- Replace browser_pull_debug_logs with simpler browser_get_url command
- Add back/forward navigation buttons to BrowserPanel and BrowserScene
- Poll webview URL to keep address bar in sync with in-page navigations
- Intercept target="_blank" links to navigate in-place (Tauri limitation)
- Reorder toolbar: back/forward/refresh before address bar
- Fix address bar overflow with proper CSS constraints
- Fix right panel width validation on mount for non-maximized windows
- Include sourceUrl in web element context for chat messages

Made-with: Cursor