refactor(ui): add stance icons to implant badge (#787)

Replace text-only stance labels with SVG icons + tint shader per D-086.
Alpha-mask shader swaps color at runtime via ShaderMaterial parameter.
Icons: walk, crouch, careful, sprint at 18px inside ImplantPanel row.
Also fix stale UILayer/HUD test path in test_ui_framework_sprint15.

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

client/shaders/icon_tint.gdshader

@@ -0,0 +1,10 @@
+shader_type canvas_item;
+// D-086: Runtime icon tint — replaces color channel with tint_color, preserves alpha mask.
+// Applied to SVG-sourced TextureRect nodes so stance/status icons can be color-coded at runtime.
+// Default: #c8d0e0 (insert chrome) — identical to the SVG's authored stroke color.
+uniform vec4 tint_color : source_color = vec4(0.784, 0.816, 0.878, 1.0);
+
+void fragment() {
+	float a = texture(TEXTURE, UV).a;
+	COLOR = vec4(tint_color.rgb, a * tint_color.a);
+}

client/tests/test_ui_framework_sprint15.gd

@@ -122,14 +122,14 @@ func test_minimap_placeholder_exists_in_ui_layer() -> void:
 	assert_that(_instance.get_node_or_null("InsertOverlay/Minimap")).is_not_null()
 
 
-func test_hud_exists_in_ui_layer() -> void:
-	# D-049: HUD must be in UILayer.
+func test_hud_exists_in_insert_overlay() -> void:
+	# D-051: HUD moved to InsertOverlay (layer 10) for bloom treatment (#786, PR #115).
 	var scene := MAIN_SCENE
 	_instance = scene.instantiate()
 	auto_free(_instance)
 	add_child(_instance)
 
-	assert_that(_instance.get_node_or_null("UILayer/HUD")).is_not_null()
+	assert_that(_instance.get_node_or_null("InsertOverlay/HUD")).is_not_null()
 
 
 func test_interaction_list_exists_in_insert_overlay() -> void:

client/ui/stance_indicator.gd

@@ -1,23 +1,33 @@
 extends Control
 
 ## D-053: Stance indicator — implant-styled badge (D-169).
-## Sprint/Walk/Careful/Crouch. Color-coded for quick read.
+## Sprint/Walk/Careful/Crouch. Icon (D-086) + color-coded label.
 
 const STANCE_COLORS := {
 	"Sprint": Color("#d45d5d"),  # Red — fast, loud, dangerous
-	"Walk": Color("#c8d0e0"),  # Default — neutral white-blue
-	"Careful": Color("#6bc9a6"),  # Green — quiet, observant
+	"Walk": Color("#c8d0e0"),    # Default — neutral white-blue
+	"Careful": Color("#6bc9a6"), # Green — quiet, observant
 	"Crouch": Color("#e8c547"),  # Amber — very quiet, slow
 }
 
+const STANCE_ICONS := {
+	"Sprint": "res://assets/icons/icon_stance_sprint.svg",
+	"Walk": "res://assets/icons/icon_stance_walk.svg",
+	"Careful": "res://assets/icons/icon_stance_careful.svg",
+	"Crouch": "res://assets/icons/icon_stance_crouch.svg",
+}
+
 var _current_stance: String = "Walk"
 var _panel: ImplantPanel
-var _row: ImplantDataRow
+var _icon: TextureRect
+var _label: Label
+var _icon_mat: ShaderMaterial
 
 
 func _ready() -> void:
 	mouse_filter = Control.MOUSE_FILTER_IGNORE
 	var theme_res := load("res://ui/implant/default_implant.tres") as ImplantTheme
+	var icon_shader := load("res://shaders/icon_tint.gdshader") as Shader
 
 	_panel = ImplantPanel.new()
 	_panel.name = "StancePanel"
@@ -25,17 +35,53 @@ func _ready() -> void:
 	_panel.mouse_filter = Control.MOUSE_FILTER_IGNORE
 	add_child(_panel)
 
-	_row = ImplantDataRow.new("Walk", STANCE_COLORS["Walk"])
-	_panel.add_component(_row)
+	var hbox := HBoxContainer.new()
+	hbox.add_theme_constant_override("separation", 4)
+	hbox.mouse_filter = Control.MOUSE_FILTER_IGNORE
+
+	_icon = TextureRect.new()
+	_icon.expand_mode = TextureRect.EXPAND_KEEP_SIZE
+	_icon.stretch_mode = TextureRect.STRETCH_KEEP_ASPECT_CENTERED
+	_icon.custom_minimum_size = Vector2(18.0, 18.0)
+	_icon.mouse_filter = Control.MOUSE_FILTER_IGNORE
+	_icon_mat = ShaderMaterial.new()
+	_icon_mat.shader = icon_shader
+	_icon_mat.set_shader_parameter("tint_color", STANCE_COLORS["Walk"])
+	_icon.material = _icon_mat
+	hbox.add_child(_icon)
+
+	_label = Label.new()
+	_label.vertical_alignment = VERTICAL_ALIGNMENT_CENTER
+	_label.mouse_filter = Control.MOUSE_FILTER_IGNORE
+	if theme_res:
+		_label.add_theme_font_size_override("font_size", theme_res.font_body)
+	hbox.add_child(_label)
+
+	_panel.add_component(hbox)
+	_apply_stance("Walk")
+
+
+func _apply_stance(stance: String) -> void:
+	_current_stance = stance
+	var color: Color = STANCE_COLORS.get(stance, Color("#c8d0e0"))
+	var icon_path: String = STANCE_ICONS.get(stance, "")
+
+	if _icon and not icon_path.is_empty():
+		var tex := load(icon_path) as Texture2D
+		if tex:
+			_icon.texture = tex
+		_icon_mat.set_shader_parameter("tint_color", color)
+
+	if _label:
+		_label.text = stance
+		_label.add_theme_color_override("font_color", color)
 
 
 func update_from_state() -> void:
 	var stance: String = GameState.player_stance
 	if stance == _current_stance:
 		return
-	_current_stance = stance
-	var color: Color = STANCE_COLORS.get(stance, Color("#c8d0e0"))
-	_row.set_content(stance, color)
+	_apply_stance(stance)
 
 
 func get_current_stance() -> String: