Initial commit: Transcience MVP

Top-down twin-stick bullet-hell, Godot 4.7, server-authoritative dedicated
server with client-side prediction. Clients send input only; the server
resolves every hit for both players and enemies (no PvP).

- SimWorld: whole simulation as plain RefCounted objects (no nodes, no
  physics server), ~0.24ms/tick at peak load -- runs headless for free and
  drives 78 tests in under a second
- BulletPool: struct-of-arrays bullet storage, replicated as spawn/despawn
  events rather than per-tick state
- Emitter framework (Ring/AimedSpread/WallGap/ArcSweep) shared by trash
  enemies and bosses -- a new boss is data in src/content/content.gd, no
  simulation changes
- The Warden of the Fold: stationary 4-phase boss built entirely on that
  format
- Lobby hub with a portal into on-demand dungeon instances; one process
  hosts the hub plus every concurrent dungeon
- Emergency escape: 3s server-owned channel, cancelled by damage
- tools/check.sh, test.sh (GUT), smoke.sh (real server + bot clients over
  ENet), bench.gd; git hooks wired to the same scripts
- docs/ARCHITECTURE.md, NETCODE.md, WORKFLOW.md, ROADMAP.md

src/view/game_scene.gd

@@ -0,0 +1,29 @@
+extends Node2D
+## Root of the playable client scene. Wires the view and HUD to whatever client
+## runtime [Net] currently has, and survives that runtime being null (during
+## connection) or replaced (on reconnect).
+
+@onready var world_view: Node2D = $WorldView
+@onready var hud: CanvasLayer = $HUD
+
+var _bound: ClientRuntime = null
+
+
+func _ready() -> void:
+	world_view.position = get_viewport_rect().size * 0.5
+	get_viewport().size_changed.connect(_recentre)
+
+
+func _recentre() -> void:
+	world_view.position = get_viewport_rect().size * 0.5
+
+
+func _process(_delta: float) -> void:
+	if Net.client != _bound:
+		_bound = Net.client
+		if _bound != null and not _bound.local_hit.is_connected(_on_local_hit):
+			_bound.local_hit.connect(_on_local_hit)
+
+
+func _on_local_hit(_damage: int) -> void:
+	hud.flash_hit()