feat(client): add tile rendering, fog overlay, and camera smoothing

Sprint 2 rendering pipeline: tiles (#129), fog (#131), camera (#116).

- tile_renderer.gd: programmatic TileSet with floor/wall/door/object
  placeholder tiles, renders from snapshot tile data
- fog_renderer.gd: TileMapLayer overlay with three visibility states
  (visible/fog-edge/hidden), computed from visible_positions data
- Camera2D: smoothing enabled (speed 6.0), 2x zoom, locked to player
- game_state.gd: stores visible_tiles and visible_positions from snapshots
- sim_bridge.gd: test data with 8x8 room, corridor, and Manhattan
  distance visibility for development without server
- Scene render order: Tiles -> FogOverlay -> Entities
- Background clear color set to near-black for unexplored areas

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

client/scripts/rendering/world_renderer.gd

@@ -2,19 +2,36 @@ extends Node2D
 
 # World renderer — manages all visual representation from GameState
 # Attached to the World node in main.tscn
+# Render order (scene tree): TileMapLayer -> FogOverlay -> Entities
 
-@onready var entity_renderer = $Entities
+@onready var tile_renderer = $TileMapLayer
 @onready var fog_renderer = $FogOverlay
+@onready var entity_renderer = $Entities
+
+var _tiles_dirty: bool = true
 
 func _ready() -> void:
 	print("WorldRenderer: Initialized")
 
 # Called each frame to update visuals from game state
 func update_from_state() -> void:
+	# Update tiles (only when tile data changes)
+	if tile_renderer and tile_renderer.has_method("update_tiles"):
+		if _tiles_dirty and GameState.visible_tiles.size() > 0:
+			tile_renderer.update_tiles(GameState.visible_tiles)
+			# Register tile positions with fog renderer for coverage
+			if fog_renderer and fog_renderer.has_method("register_tile_positions"):
+				fog_renderer.register_tile_positions(GameState.visible_tiles)
+			_tiles_dirty = false
+
+	# Update fog overlay
+	if fog_renderer and fog_renderer.has_method("update_fog"):
+		fog_renderer.update_fog(GameState.visible_positions, GameState.player_position)
+
 	# Update entity sprites
 	if entity_renderer and entity_renderer.has_method("update_entities"):
 		entity_renderer.update_entities(GameState.visible_entities)
 
-	# Update fog overlay (fog data will come in D-020 expansion)
-	if fog_renderer and fog_renderer.has_method("update_fog"):
-		fog_renderer.update_fog({}, GameState.player_position)
+# Mark tiles as needing re-render (call when tile data changes significantly)
+func invalidate_tiles() -> void:
+	_tiles_dirty = true