Windows title bar material fix

Windows title bar material isolation

PaneFlow 0.8.2 is a focused patch release for an important Windows desktop material boundary. When the terminal enabled the host-window backdrop while the dedicated chrome material was disabled, the transparent title bar could expose terminal-only Mica instead of the configured theme background.

The Windows title bar now paints an opaque theme surface whenever its own material is disabled. It remains transparent when the chrome material is intentionally active, preserving the native backdrop. Linux and macOS keep their existing chrome behavior.

Regression coverage

• Added a Windows-specific test covering both disabled and active chrome material states.
• Kept the non-Windows transparency assertion explicitly scoped to Linux and macOS behavior.
• Preserved the existing opaque Linux shell and native macOS/Windows sidebar material contracts.

Documentation and project state

• Updated the architecture guide to describe the shipped dual terminal stack: pinned libghostty-vt by default on Linux and Windows x64 MSVC, with Alacritty on macOS and as the explicit cross-platform rollback.
• Refreshed the README with the current Windows backend, installation paths, rollback setting, and a direct evaluator quick-test path.
• Finalized the Build Week implementation evidence, platform matrix, validation claims, and traction copy against the shipped v0.8.1 baseline.
• Removed the stale French Build Week duplicate so the English submission document remains the canonical public account.
• Corrected the top-level changelog and added the final submission audit record used to verify the public claims against code and release artifacts.

No configuration, session format, terminal backend selection, or packaging contract changed in this patch.

Install and validation

Download the signed artifacts from this release or use the installation instructions.

The v0.8.2 release pipeline passed Linux x86_64 and ARM64 packaging, the signed and notarized macOS ARM64 DMG, the signed Windows x64 MSI, Ubuntu, Debian, Fedora, openSUSE and Arch smoke tests, Windows install and upgrade validation, and Linux auto-update E2E. The release contains 35 verified assets with SHA-256 sidecars and Minisign signatures where applicable.

Full Changelog: v0.8.1...v0.8.2