feat(client): add BoneAttachment3D overhead anchor above Head bone (#712)

Infrastructure for floating UI elements (status indicators, thought
bubbles, alert markers). Marker3D at Vector3(0, 0.3, 0) offset from
Head bone, exposed via get_overhead_anchor() public API.

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

client/scripts/rendering/character_visual.gd

@@ -23,6 +23,7 @@ extends Node3D
 ##   get_clothing_node_count()            — number of clothing MeshInstance3D nodes
 ##   get_accessory_node_count()           — number of accessory BoneAttachment3D nodes
 ##   get_skin_tone_texture_name(index)    — skin tone texture filename key for index
+##   get_overhead_anchor()                — Marker3D above Head bone for floating UI (#712)
 ##
 ## D-159 (11 body types), D-160 (18 segments), D-161 (head separate),
 ## D-162 (clothing pre-fitted), D-163 (heads via BoneAttachment3D), D-164 (skeleton fork)
@@ -101,6 +102,8 @@ var _clothing_meshes: Array[MeshInstance3D] = []
 var _bone_attachments: Array[BoneAttachment3D] = []
 var _outline_nodes: Array[MeshInstance3D] = []
 var _accessory_attachments: Array[BoneAttachment3D] = []
+var _overhead_anchor: Marker3D = null
+var _overhead_attachment: BoneAttachment3D = null
 
 # Inspectable state for tests
 var _active_torso_variant: String = "full"
@@ -218,6 +221,13 @@ func get_skin_tone_texture_name(index: int) -> String:
 	return SKIN_TONES[clampi(index, 0, SKIN_TONES.size() - 1)]["tex"]
 
 
+## Return the overhead anchor Marker3D (#712). Null if skeleton not loaded.
+## Anchor point for floating UI elements: status indicators, thought bubbles,
+## alert markers, speech icons. Positioned ~0.3m above the Head bone.
+func get_overhead_anchor() -> Marker3D:
+	return _overhead_anchor
+
+
 # =============================================================================
 # Internal — teardown
 # =============================================================================
@@ -234,6 +244,13 @@ func _clear() -> void:
 			node.free()
 	_outline_nodes.clear()
 
+	# #712: free overhead anchor before general bone attachments
+	if is_instance_valid(_overhead_attachment) and _overhead_attachment.get_parent():
+		_overhead_attachment.get_parent().remove_child(_overhead_attachment)
+		_overhead_attachment.free()
+	_overhead_attachment = null
+	_overhead_anchor = null
+
 	for att in _bone_attachments:
 		if is_instance_valid(att) and att.get_parent():
 			att.get_parent().remove_child(att)
@@ -291,6 +308,7 @@ func _load_skeleton() -> void:
 		for m in armature_meshes:
 			print("  armature mesh: ", m.name, " visible=", m.visible)
 	_validate_slot_bones()
+	_create_overhead_anchor()
 
 
 ## Warn on any SLOT_TO_BONE entry that doesn't exist in the loaded skeleton.
@@ -302,6 +320,27 @@ func _validate_slot_bones() -> void:
 			push_warning("CharacterVisual: SLOT_TO_BONE['%s'] = '%s' — bone not found in skeleton" % [slot, bone_name])
 
 
+## #712: Create a Marker3D anchored ~0.3m above the Head bone via BoneAttachment3D.
+## Anchor point for floating UI elements (status indicators, thought bubbles, etc.).
+func _create_overhead_anchor() -> void:
+	if _skeleton == null:
+		return
+	var bone_idx := _skeleton.find_bone("Head")
+	if bone_idx == -1:
+		push_warning("CharacterVisual: Head bone not found — overhead anchor not created")
+		return
+	_overhead_attachment = BoneAttachment3D.new()
+	_overhead_attachment.bone_name = "Head"
+	_overhead_attachment.bone_idx = bone_idx
+	_overhead_attachment.name = "OverheadAttachment"
+	_skeleton.add_child(_overhead_attachment)
+
+	_overhead_anchor = Marker3D.new()
+	_overhead_anchor.name = "OverheadAnchor"
+	_overhead_anchor.position = Vector3(0, 0.3, 0)
+	_overhead_attachment.add_child(_overhead_anchor)
+
+
 # =============================================================================
 # Internal — body segments (D-160)
 # =============================================================================