KeeperFX Linux Alpha 1.4.0.5296

Weekly upstream sync — merges the KeeperFX team's latest alpha patches (19 commits, #5019–#5049). Verified to build clean on Linux before release.

Engine performance (single-player):

• gpoly polygon rasterizer optimized for ~10% faster rendering (#5043)
• Map-parchment (minimap) redraw performance fixed (#5041)

New feature:

• Map-specific sounds and speeches — maps can ship custom sounds/speech in their .zip bundle (#5019)

Gameplay/engine fixes:

• Menu-sound gating fixed (#5028), mouse-light flicker on GUI menus fixed (#5040)
• Highscore input caret scaled/shaded/framed correctly (#5044)
• Computer players no longer sell enemy traps when building rooms (#5034)
• pngpal2raw tool build error fixed (#5035)

Maps: Fortress added, Bash neutered, Dread Mountain fixed (#5032)

Controller: rumble only fires when a controller was the last input used (#5049)

Multiplayer: reliable slap/power-click (#5026), version-mismatch message (#5025), client clock synced to host (#5031), dynamic input-lag (#5033, #5036), desync fixes + logging (#5042), ghost-tagging fix (#5030), fixed pickup+cast at once (#5038), client-side info buttons (#5045)

The .flatpak refreshes on its monthly build; existing installs self-update to this engine on first launch.