Integrate Kenney Starter Kit FPS assets + comprehensive test suite

Assets (CC0 license):
- 3D models: Blaster gun, walls, platforms, grass, clouds, enemy
- Sounds: blaster fire, impacts, footsteps, jumps, weapon change
- Sprites: crosshair, hit marker, muzzle flash, skybox, blob shadow
- Font: Lilita One

Code changes:
- weapon_manager.gd: load blaster.glb as gun model (replaces box mesh)
- player.tscn: use Kenney sounds (blaster.ogg, enemy_hurt/destroy) and crosshair

Test suite (100 unit tests + 4 integration scenarios):
- weapon_data.gd: 27 tests — all 6 weapons every stat verified
- economy.gd: 19 tests — constants, loss streak, buy thresholds
- bomb.gd: 15 tests — state machine, timing constants
- round_manager.gd: 10 tests — win conditions, elimination logic
- team_manager.gd: 8 tests — auto-balance, team assignment
- headless_test_bot.gd: integration bot with movement/idle/rounds scenarios
- run_multi_bot.sh: multi-client launcher

assets/kenney-fps/objects/cloud.gd

@@ -0,0 +1,19 @@
+extends Node3D
+
+var time = 0.0
+
+var random_number = RandomNumberGenerator.new()
+
+var random_velocity:float
+var random_time:float
+
+func _ready():
+	
+	random_velocity = random_number.randf_range(0.1, 2.0)
+	random_time = random_number.randf_range(0.1, 2.0)
+
+func _process(delta):
+	
+	position.y += (cos(time * random_time) * random_velocity) * delta # Sine movement
+	
+	time += delta