feat(client): initialize Godot 4 project boilerplate (epic #277)

Set up the complete Godot 4.6 client foundation as a pure renderer (D-020):
- project.godot with 2D rendering, autoloads, input actions
- Main scene: Game > World (TileMapLayer, Entities, FogOverlay) + Camera2D + UILayer
- Autoloads: SimBridge (connection state machine + test mode), GameState, InputMapper
- Rendering stubs: WorldRenderer, EntityRenderer, FogRenderer
- UI stubs: HUD (health/perception/time), Minimap, MonologueDisplay
- Input mapping: WASD/arrows, E (interact), Tab (perception), Esc (menu), Space (pause)
- gdUnit4 smoke tests: scene loads, autoloads registered (2/2 passing)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/scripts/autoloads/sim_bridge.gd

@@ -0,0 +1,80 @@
+extends Node
+
+# Connection states
+enum ConnectionState { DISCONNECTED, CONNECTING, CONNECTED, ERROR }
+
+var state: ConnectionState = ConnectionState.DISCONNECTED
+var test_mode: bool = true  # Enable test mode for development without Rust server
+
+# Signals
+signal connection_state_changed(old_state: ConnectionState, new_state: ConnectionState)
+signal snapshot_received(snapshot: Dictionary)
+
+func _ready() -> void:
+	if test_mode:
+		print("SimBridge: Running in test mode (hardcoded snapshot)")
+
+# Change connection state and emit signal
+func _set_state(new_state: ConnectionState) -> void:
+	if state != new_state:
+		var old_state = state
+		state = new_state
+		connection_state_changed.emit(old_state, new_state)
+
+# Connect to simulation server (real implementation comes later)
+func connect_to_sim() -> void:
+	_set_state(ConnectionState.CONNECTING)
+	# TODO: Actual connection logic when IPC/MessagePack is implemented
+	if test_mode:
+		_set_state(ConnectionState.CONNECTED)
+	else:
+		_set_state(ConnectionState.ERROR)
+
+# Disconnect from simulation server
+func disconnect_from_sim() -> void:
+	_set_state(ConnectionState.DISCONNECTED)
+
+# Send input to simulation (real implementation comes later)
+func send_input(player_input: Dictionary) -> void:
+	if state != ConnectionState.CONNECTED:
+		return
+	# TODO: Serialize and send via MessagePack when IPC is implemented
+	pass
+
+# Poll for snapshot from simulation
+func poll_snapshot() -> Variant:
+	if state != ConnectionState.CONNECTED:
+		return null
+
+	if test_mode:
+		var snapshot = _test_snapshot()
+		snapshot_received.emit(snapshot)
+		return snapshot
+
+	# TODO: Actual polling logic when IPC/MessagePack is implemented
+	return null
+
+# Hardcoded test snapshot for development
+func _test_snapshot() -> Dictionary:
+	return {
+		"tick": Time.get_ticks_msec() / 100,  # Increment over time for testing
+		"player": {
+			"position": [10, 10],
+			"health": 100
+		},
+		"entities": [
+			{
+				"id": 1,
+				"type": "npc",
+				"position": [12, 8],
+				"name": "Test NPC"
+			},
+		],
+		"fog": {
+			"radius": 8
+		},
+		"hud": {
+			"perception_mode": "baseline",
+			"time": "08:00"
+		}
+	}