Separate workflow (not ci.yml) so the ~20-40min Rust/AppImage build only runs on
desktop/** changes, not every backend/frontend push. Builds on the ci-tauri:1.97
image: frontend build -> `cargo tauri icon app-icon.png` (from a committed 1024px
source PNG, sidestepping SVG-input questions) -> cargo fmt --check -> clippy -D
warnings -> cargo test -> `cargo tauri build` (deb + AppImage).
APPIMAGE_EXTRACT_AND_RUN=1 for FUSE-less CI containers. Verifies the M10.2 scaffold
end-to-end and is the foundation for the integrated-AppImage work (task 2013).
Also updates ci-requirements.md with the desktop lane.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FRgehjoz7Yv8LkUfADxACm
