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

gore.gd

@@ -0,0 +1,15 @@
+extends Node
+## Stateless façade (autoload `Gore`) for spawning persistent blood splats. Callers just say
+## Gore.splat(pos, dir, size) at each wound; this routes to the level's BloodDecals pool
+## (group &"blood_decals"), which the game shell rebuilds into LevelRoot on every load so the
+## stains die with the level. No-ops when there's no pool (menus, headless tests without a
+## level) or when the player has turned gore off — so the gate lives in one place.
+
+
+func splat(world_pos: Vector3, dir: Vector3 = Vector3.ZERO, size: float = 0.6) -> void:
+	if not Settings.gore:
+		return
+	var pool := get_tree().get_first_node_in_group(&"blood_decals")
+	if pool == null:
+		return
+	pool.call(&"splat", world_pos, dir, size * DP.f("blood_scale"))