feat(client): character creation screen with live 3D preview (#705)

Full character creation UI with 5-tab customisation panel (Body, Head,
Hair, Clothing, Accessories), live 3D compositor preview via SubViewport,
D-165 color picker modal, keyboard navigation, and game flow integration.

- CharacterCreation scene + script (~1440 lines) implementing wireframe spec
- SubViewport with Camera3D (frontal/dramatic/overhead presets per D-158)
- Cardinal rotation (Q/E) per D-155, randomise (R), Tab/Enter/Esc navigation
- Body type grid (11 types, D-159), skin tone dock (9 tones, shared state)
- Head template, hair, facial hair, eyebrow grids with DirAccess asset scanning
- Clothing slot selector with per-item Primary/Secondary/Accent tints
- Accessory slot selector with Primary/Secondary tints (Array[Color] descriptor)
- 54-swatch color picker modal (D-165) with hex input and recent colors
- Auto-derive flags for highlight, eyebrow tint, facial hair tint from hair primary
- Game flow: main_menu → archetype select → character creation → game start
- GameState.character_visual_descriptor field for gameplay consumption
- Updated accessory_tints from single Color to Array[Color] in descriptor + compositor
- 40+ GdUnit tests covering scene structure, signals, keyboard nav, color derivation

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

client/ui/main_menu.gd

@@ -7,6 +7,7 @@ extends Control
 
 const GAME_SCENE := "res://scenes/main.tscn"
 const CHARACTER_SELECT_SCENE := "res://scenes/character_select.tscn"
+const CHARACTER_CREATION_SCENE := "res://scenes/character_creation.tscn"
 
 const BG_COLOR := Color(0.05, 0.05, 0.08, 1.0)
 const TITLE_COLOR := Color("#c8d0e0")
@@ -25,7 +26,8 @@ const FONT_SIZE_BTN := 15
 @onready var _saves_list: VBoxContainer = $LoadGamePanel/VBox/SavesScroll/SavesList
 @onready var _load_back_btn: Button = $LoadGamePanel/VBox/BackBtn
 
-var _char_select: Control = null  # Instantiated on demand
+var _char_select: Control = null    # Instantiated on demand
+var _char_creation: Control = null  # Instantiated after archetype confirmed
 
 
 func _ready() -> void:
@@ -68,14 +70,9 @@ func _on_archetype_confirmed(archetype: String) -> void:
 	if _char_select != null and is_instance_valid(_char_select):
 		_char_select.queue_free()
 		_char_select = null
-	# Set archetype before new_game() so SessionManager can persist it.
+	# Set archetype first; save dir created after character creation confirms.
 	GameState.character_archetype = archetype
-	var game_id := SessionManager.new_game()
-	if game_id.is_empty():
-		push_error("MainMenu: new_game() failed to create save directory — cannot start")
-		return
-	SessionManager.save_character_archetype(game_id, archetype)
-	get_tree().change_scene_to_file(GAME_SCENE)
+	_show_character_creation()
 
 
 func _on_archetype_cancelled() -> void:
@@ -84,6 +81,45 @@ func _on_archetype_cancelled() -> void:
 		_char_select = null
 
 
+func _show_character_creation() -> void:
+	if _char_creation != null and is_instance_valid(_char_creation):
+		_char_creation.queue_free()
+	var scene := load(CHARACTER_CREATION_SCENE) as PackedScene
+	if scene == null:
+		push_error("MainMenu: failed to load character_creation.tscn — skipping to game")
+		_start_game_with_defaults()
+		return
+	_char_creation = scene.instantiate()
+	add_child(_char_creation)
+	_char_creation.creation_confirmed.connect(_on_creation_confirmed)
+	_char_creation.creation_cancelled.connect(_on_creation_cancelled)
+
+
+func _on_creation_confirmed(descriptor: CharacterVisualDescriptor) -> void:
+	if _char_creation != null and is_instance_valid(_char_creation):
+		_char_creation.queue_free()
+		_char_creation = null
+	GameState.character_visual_descriptor = descriptor
+	_start_game_with_defaults()
+
+
+func _on_creation_cancelled() -> void:
+	if _char_creation != null and is_instance_valid(_char_creation):
+		_char_creation.queue_free()
+		_char_creation = null
+	# Return to archetype select
+	_show_character_select()
+
+
+func _start_game_with_defaults() -> void:
+	var game_id := SessionManager.new_game()
+	if game_id.is_empty():
+		push_error("MainMenu: new_game() failed to create save directory — cannot start")
+		return
+	SessionManager.save_character_archetype(game_id, GameState.character_archetype)
+	get_tree().change_scene_to_file(GAME_SCENE)
+
+
 func _on_continue() -> void:
 	GameState.pending_load_path = ""  # clear stale load path from previous Load selection
 	var saves := SessionManager.list_game_dirs()