feat(client): upgrade protocol decoder and GameState for v2 snapshot

Server shipped ObserverSnapshot v2 with game_time, player_facing,
visible_tiles (with visibility sectors), and per-entity visibility.
Protocol decoder was silently ignoring these fields. Now extracts
all v2 data with null defaults for backward compatibility.

GameState gains game_time, player_facing, visibility_sectors vars.
Derives visible_positions from visible_tiles when present (for real
server mode). Test snapshot updated with v2 fields.

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

client/scripts/autoloads/game_state.gd

@@ -10,6 +10,11 @@ var visible_entities: Array = []
 var visible_tiles: Array = []
 var visible_positions: Dictionary = {}  # Vector2i -> true, for fast fog lookups
 
+# v2 fields (D-015, D-031)
+var game_time: Dictionary = {}  # {day, time_of_day, day_phase, paused} or empty
+var player_facing: String = "North"  # 8-directional facing direction
+var visibility_sectors: Dictionary = {}  # Vector2i -> "Forward"/"Peripheral"
+
 # Player entity ID — the first entity is assumed to be the player (will be
 # refined when the server assigns explicit player entity IDs).
 var player_entity_id: int = 1
@@ -40,3 +45,25 @@ func apply_snapshot(snapshot: Dictionary) -> void:
 		visible_positions.clear()
 		for pos in snapshot.visible_positions:
 			visible_positions[Vector2i(pos.x, pos.y)] = true
+
+	# v2: game_time (D-031)
+	if snapshot.has("game_time") and snapshot.game_time is Dictionary:
+		game_time = snapshot.game_time
+
+	# v2: player_facing (D-015)
+	if snapshot.has("player_facing") and snapshot.player_facing is String:
+		player_facing = snapshot.player_facing
+
+	# v2: visible_tiles with visibility sectors
+	# Derives visible_positions when not explicitly provided (real server mode)
+	if snapshot.has("visible_tiles") and snapshot.visible_tiles is Array and snapshot.visible_tiles.size() > 0:
+		visibility_sectors.clear()
+		var has_explicit_positions := snapshot.has("visible_positions")
+		if not has_explicit_positions:
+			visible_positions.clear()
+		for vtile in snapshot.visible_tiles:
+			var pos := Vector2i(vtile.x, vtile.y)
+			if vtile.has("visibility"):
+				visibility_sectors[pos] = vtile.visibility
+			if not has_explicit_positions:
+				visible_positions[pos] = true

client/scripts/autoloads/sim_bridge.gd

@@ -240,6 +240,14 @@ func _test_snapshot() -> Dictionary:
 	_test_tick += 1
 	return {
 		"tick": _test_tick,
+		"version": 2,
+		"game_time": {
+			"day": 0,
+			"time_of_day": 0,
+			"day_phase": "Morning",
+			"paused": false,
+		},
+		"player_facing": "North",
 		"entities": [
 			{
 				"entity_id": 1,
@@ -247,6 +255,7 @@ func _test_snapshot() -> Dictionary:
 				"y": 10.0,
 				"z": 0,
 				"kind": { "variant": "Player", "data": null },
+				"visibility": "Forward",
 			},
 			{
 				"entity_id": 2,
@@ -254,9 +263,11 @@ func _test_snapshot() -> Dictionary:
 				"y": 10.0,
 				"z": 0,
 				"kind": { "variant": "Npc", "data": null },
+				"visibility": "Peripheral",
 			},
 		],
 		"tiles": _test_tiles(),
+		"visible_tiles": _test_visible_tiles(),
 		"visible_positions": _test_visible_positions(),
 	}
 
@@ -292,6 +303,27 @@ func _test_tiles() -> Array:
 
 	return tiles
 
+# Test visible tiles with visibility sectors (v2 format)
+# Tiles ahead of the player (y <= player_y) are Forward, others Peripheral.
+func _test_visible_tiles() -> Array:
+	var vtiles: Array = []
+	var player_x := 10
+	var player_y := 10
+	var radius := 4
+	var room_x := 7
+	var room_y := 7
+	var room_w := 8
+	var room_h := 8
+
+	for x in range(player_x - radius, player_x + radius + 1):
+		for y in range(player_y - radius, player_y + radius + 1):
+			var dist := absf(x - player_x) + absf(y - player_y)
+			if dist <= radius:
+				if x >= room_x and x < room_x + room_w and y >= room_y and y < room_y + room_h:
+					var sector: String = "Forward" if y <= player_y else "Peripheral"
+					vtiles.append({"x": x, "y": y, "z": 0, "visibility": sector})
+	return vtiles
+
 # Test visibility: player at (10,10) can see tiles within radius 4, blocked by walls
 func _test_visible_positions() -> Array:
 	var positions: Array = []