2.2.9-alpha

Fixes the reports in #124, #125 and #126.

• Boss Rush boss defeats no longer leave X permanently invincible.
• Subtanks start with the original full value and empty tanks cannot refill health. Older Boss Rush saves with invalid empty-tank values recover automatically.
• Chill Penguin's ice effect keeps the player frozen.
• Boomer Kuwanger stays inside the arena and recovers from an existing position behind a closed door.
• The Linux AppImage honors keybinds.ini beside the AppImage when starting gameplay and reloading controls.
• MSU-1 music resumes after a Light Capsule's fade-out stops playback.

Also includes the Storm Eagle and Magic Carpet fixes already on main.

Validated on Windows and Linux, with all 28 boss pairs in solo and both local co-op character orders, native damage/weakness checks, save-state replay, and packaged startup, Boss Rush combat, rendering and control persistence. CTest coverage passes; two optional Saber asset tests are skipped. MSU fade/resume uses the real PCM device in a muted test.

Download the Windows ZIP or Linux x86_64 AppImage below. Both players should update before starting a new netplay session.

Changes: #127

For future gameplay reports, please attach the complete replay session and its sidecars using the reporting instructions.

When retesting #124, start a fresh Boss Rush run. Save states recorded while X was already stuck invincible retain that older state. The supplied replay checkpoints and keyboard bindings were also checked against these fixes.