Summary
- Add validated per-window bounds, centering, resizability, fullscreen, and size constraints to the Linux GTK and Windows Win32 bridges.
- Preserve sender-scoped routing and reset control state on close/reopen.
- Extend the existing Xvfb/WebView2 multi-window smoke and document window-manager caveats.
Local verification
- Pinned Zig unit tests for shared controls and registry passed.
- Windows target test binary cross-compiled with pinned Zig.
- SDK: 575 passed; TypeScript typecheck passed; pickier: 0 errors (existing warnings).
CI
Please wait for Linux GUI, Windows WebView2, and all required checks before merge. No release/tag is part of this PR.