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/main.gd

@@ -0,0 +1,31 @@
+extends Node2D
+
+@onready var world_renderer = $World
+@onready var hud = $UILayer/HUD
+
+func _ready() -> void:
+	print("The Settled Reach — client initialized")
+
+	# Connect to simulation (will use test mode initially)
+	SimBridge.connect_to_sim()
+
+func _process(_delta: float) -> void:
+	# Main game loop: poll snapshot, apply state, flush input
+	var snapshot = SimBridge.poll_snapshot()
+	if snapshot != null:
+		GameState.apply_snapshot(snapshot)
+
+		# Update renderers with new state
+		if world_renderer and world_renderer.has_method("update_from_state"):
+			world_renderer.update_from_state()
+
+		# Update HUD
+		if hud and hud.has_method("update_from_hud_data"):
+			hud.update_from_hud_data(GameState.hud_data)
+			if snapshot.has("player") and snapshot.player.has("health"):
+				hud.update_health(snapshot.player.health)
+
+	# Send queued input to simulation
+	var inputs = InputMapper.flush_queue()
+	for input in inputs:
+		SimBridge.send_input(input)