Add blood decals, gore, mobile HUD, web start gate + touch/perf tests

Remove tools/fstest.html scratch page used to probe browser
fullscreen/orientation APIs.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EznnY8rH2dXhtono1kwsXg

project.godot

@@ -28,6 +28,8 @@ DebugDraw="*res://debug_draw.gd"
 Settings="*res://settings.gd"
 Run="*res://levels/run_state.gd"
 OrientationGuard="*res://orientation_guard.gd"
+WebStartGate="*res://web_start_gate.gd"
+Gore="*res://gore.gd"
 
 [display]