Mega Man X4 Recompiled — v0.1.1-coop-playtest.10

Windows ZIP and Linux x86_64 AppImage. Both peers must use this release.
Unified cameras and Stacked lifebars remain defaults; Split remains experimental.

• Fixes private special-weapon graphics sampling the wrong part of their texture.
• Fixes P2 and the co-op HUD disappearing after exhausting private texture slots.
  The host texture cache now safely reuses slots that neither player's queued
  drawing commands reference, including after saving and loading.
• Fixes P2 disappearing during an upgrade capsule's shared palette effects.
• Fixes Web Spider's waterfall exit stalling when P1 is dead and P2 reaches it.
  The surviving player can complete the exit and arrive in the next section.

The reported Frozen Zero problem on Split Mushroom's second rotating staircase
remains unresolved. Its supplied recording does not reproduce a character-state
lock; movement inputs are absent during the reported stall. This release does
not claim to fix the underlying input-delivery problem or every disappearance.

For bug reports, quit normally and zip the complete saves/diagnostics folder
beside the executable or AppImage. Keep Playtest Diagnostics enabled and include
video when possible. Startup logging fixes from Playtest 9 are included.
See the numbered checklist.