Avatar customization: drag-to-rotate preview, fill the dead space, seam fix

- The preview is now a turntable: drag it to rotate the avatar and see all
  sides; it slowly auto-spins after ~2.5s of no input. Starts facing the
  camera so you see the face. "drag to rotate" hint under the viewport.
- The big grey void to the right of the controls is gone -- the preview
  panel now expands to fill the leftover width; the controls dock to the
  right edge at a fixed width.
- Camera reframed to fit the whole ~2 m body; softer preview lights.
- Placeholder avatar: torso/arms/legs now share one 0.46 m depth so a limb
  always covers the torso slice behind it -- kills the bright "cyan seam"
  (it was a lit sliver of the torso side peeking past the thinner arm).

Verified headless (boot, 2p multiplayer, avatar smoke source+pack,
fresh-clone) + eyeballed the customization screen and the avatar seams in
rendered screenshots.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015jtxAiu5dAW4WxCNdGkrkJ

scripts/avatar/avatar_customization_ui.gd

@@ -76,6 +76,16 @@ var _preview_root: Node3D = null
 ## Currently selected slot id.
 var _selected_slot: String = ""
 
+## Turntable: the preview avatar's Y rotation (radians), whether the player is
+## currently dragging it, and how long since they last touched it (drives the
+## slow idle auto-spin). Starts facing the camera.
+var _turntable_yaw: float = PI
+var _turntable_dragging: bool = false
+var _turntable_idle: float = 0.0
+const _TURNTABLE_IDLE_SPIN_DELAY := 2.5
+const _TURNTABLE_IDLE_SPIN_SPEED := 0.5
+const _TURNTABLE_DRAG_SPEED := 0.01
+
 ## UI node references.
 var _slot_list: VBoxContainer = null
 var _item_list: VBoxContainer = null
@@ -142,10 +152,11 @@ func _build_ui() -> void:
 	root_hbox.add_theme_constant_override("separation", 16)
 	add_child(root_hbox)
 
-	# --- Left: preview ---
+	# --- Left: preview (takes all the leftover width) ---
 	var preview_panel := PanelContainer.new()
 	preview_panel.name = "PreviewPanel"
-	preview_panel.custom_minimum_size = Vector2(480, 0)
+	preview_panel.custom_minimum_size = Vector2(420, 0)
+	preview_panel.size_flags_horizontal = Control.SIZE_EXPAND_FILL
 	root_hbox.add_child(preview_panel)
 
 	var preview_margin := MarginContainer.new()
@@ -155,15 +166,30 @@ func _build_ui() -> void:
 	preview_margin.add_theme_constant_override("margin_bottom", 8)
 	preview_panel.add_child(preview_margin)
 
+	var preview_vbox := VBoxContainer.new()
+	preview_vbox.add_theme_constant_override("separation", 6)
+	preview_margin.add_child(preview_vbox)
+
 	_preview_container = SubViewportContainer.new()
 	_preview_container.name = "PreviewViewportContainer"
 	_preview_container.stretch = true
-	_preview_container.custom_minimum_size = Vector2(464, 560)
-	preview_margin.add_child(_preview_container)
+	_preview_container.custom_minimum_size = Vector2(400, 520)
+	_preview_container.size_flags_horizontal = Control.SIZE_EXPAND_FILL
+	_preview_container.size_flags_vertical = Control.SIZE_EXPAND_FILL
+	_preview_container.mouse_filter = Control.MOUSE_FILTER_STOP
+	_preview_container.gui_input.connect(_on_preview_gui_input)
+	preview_vbox.add_child(_preview_container)
+
+	var rotate_hint := Label.new()
+	rotate_hint.text = "drag to rotate"
+	rotate_hint.horizontal_alignment = HORIZONTAL_ALIGNMENT_CENTER
+	rotate_hint.add_theme_color_override("font_color", Color(1, 1, 1, 0.5))
+	rotate_hint.add_theme_font_size_override("font_size", 12)
+	preview_vbox.add_child(rotate_hint)
 
 	_preview_viewport = SubViewport.new()
 	_preview_viewport.name = "PreviewViewport"
-	_preview_viewport.size = Vector2i(464, 560)
+	_preview_viewport.size = Vector2i(400, 520)
 	_preview_viewport.render_target_update_mode = SubViewport.UPDATE_ALWAYS
 	_preview_viewport.transparent_bg = true
 	# Its own 3D world -- a SubViewport that shares the (Control-only) main
@@ -178,17 +204,17 @@ func _build_ui() -> void:
 	env.background_mode = Environment.BG_COLOR
 	env.background_color = Color(0.10, 0.11, 0.14)
 	env.ambient_light_source = Environment.AMBIENT_SOURCE_COLOR
-	env.ambient_light_color = Color(0.6, 0.6, 0.65)
-	env.ambient_light_energy = 1.0
+	env.ambient_light_color = Color(0.62, 0.64, 0.7)
+	env.ambient_light_energy = 0.7
 	world_env.environment = env
 	_preview_viewport.add_child(world_env)
 
-	# Camera for the preview.
+	# Camera for the preview -- framed to fit the full ~2 m avatar.
 	_preview_camera = Camera3D.new()
 	_preview_camera.name = "PreviewCamera"
 	# look_at needs a global transform, which only exists once in the tree.
 	_preview_camera.look_at_from_position(
-		Vector3(0, 1.0, 3.2), Vector3(0, 0.9, 0), Vector3.UP)
+		Vector3(0, 1.05, 3.5), Vector3(0, 0.98, 0), Vector3.UP)
 	_preview_camera.current = true
 	_preview_viewport.add_child(_preview_camera)
 
@@ -201,12 +227,12 @@ func _build_ui() -> void:
 	var key := DirectionalLight3D.new()
 	key.name = "PreviewKeyLight"
 	key.rotation_degrees = Vector3(-35, 35, 0)
-	key.light_energy = 1.2
+	key.light_energy = 1.0
 	_preview_viewport.add_child(key)
 	var fill := DirectionalLight3D.new()
 	fill.name = "PreviewFillLight"
 	fill.rotation_degrees = Vector3(-20, -140, 0)
-	fill.light_energy = 0.4
+	fill.light_energy = 0.35
 	_preview_viewport.add_child(fill)
 
 	# --- Right: controls ---
@@ -403,6 +429,31 @@ func _on_equip_pressed(asset_id: String) -> void:
 	loadout_changed.emit(loadout)
 
 
+# ---------------------------------------------------------------------------
+# Turntable (drag to rotate the preview, slow auto-spin when idle)
+# ---------------------------------------------------------------------------
+
+func _process(delta: float) -> void:
+	if _preview_root == null:
+		return
+	if _turntable_dragging:
+		_turntable_idle = 0.0
+	else:
+		_turntable_idle += delta
+		if _turntable_idle > _TURNTABLE_IDLE_SPIN_DELAY:
+			_turntable_yaw += delta * _TURNTABLE_IDLE_SPIN_SPEED
+	_preview_root.rotation.y = _turntable_yaw
+
+
+func _on_preview_gui_input(event: InputEvent) -> void:
+	if event is InputEventMouseButton and event.button_index == MOUSE_BUTTON_LEFT:
+		_turntable_dragging = event.pressed
+		_turntable_idle = 0.0
+	elif event is InputEventMouseMotion and _turntable_dragging:
+		_turntable_yaw -= event.relative.x * _TURNTABLE_DRAG_SPEED
+		_turntable_idle = 0.0
+
+
 # ---------------------------------------------------------------------------
 # Preview refresh
 # ---------------------------------------------------------------------------