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

addons/gut/gui/ShellOutOptions.tscn

@@ -0,0 +1,34 @@
+[gd_scene load_steps=2 format=3 uid="uid://ckv5eh8xyrwbk"]
+
+[ext_resource type="Script" uid="uid://c64u22kybimgi" path="res://addons/gut/gui/ShellOutOptions.gd" id="1_ht2pf"]
+
+[node name="ShellOutOptions" type="ConfirmationDialog"]
+oversampling_override = 1.0
+title = "GUT Run Mode (Experimental)"
+position = Vector2i(0, 36)
+size = Vector2i(516, 557)
+visible = true
+script = ExtResource("1_ht2pf")
+
+[node name="ScrollContainer" type="ScrollContainer" parent="."]
+custom_minimum_size = Vector2(500, 500)
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+offset_left = 8.0
+offset_top = 8.0
+offset_right = -8.0
+offset_bottom = -49.0
+grow_horizontal = 2
+grow_vertical = 2
+
+[node name="VBoxContainer" type="VBoxContainer" parent="ScrollContainer"]
+layout_mode = 2
+size_flags_horizontal = 3
+size_flags_vertical = 3
+
+[node name="AcceptDialog" type="AcceptDialog" parent="."]
+oversampling_override = 1.0
+size = Vector2i(399, 106)
+dialog_text = "Invalid arguments.  The following cannot be used:
+-d --debug -s --script"