feat(mana): HUD 蓝条（ProgressBar，每帧刷新）

scenes/main/combat_s2.gd

@@ -26,6 +26,7 @@ var _lbl_deck:    Label = null
 var _lbl_dps:     Label = null
 var _lbl_charge:  Label = null
 var _lbl_statuses: Label = null
+var _mana_bar: ProgressBar = null
 
 var _dps_poll_timer: float = 0.0
 
@@ -229,6 +230,19 @@ func _setup_hud() -> void:
 	_lbl_charge = make_label.call(Vector2(200, 62))
 	_lbl_deck   = make_label.call(Vector2(20, 122), 13)
 	_lbl_statuses = make_label.call(Vector2(20, 142), 13)
+	_mana_bar = ProgressBar.new()
+	_mana_bar.position = Vector2(200, 86)
+	_mana_bar.custom_minimum_size = Vector2(170, 16)
+	_mana_bar.size = Vector2(170, 16)
+	_mana_bar.min_value = 0.0
+	_mana_bar.show_percentage = false
+	var mana_fill := StyleBoxFlat.new()
+	mana_fill.bg_color = Color(0.3, 0.55, 1.0)
+	_mana_bar.add_theme_stylebox_override("fill", mana_fill)
+	var mana_bg := StyleBoxFlat.new()
+	mana_bg.bg_color = Color(0.12, 0.12, 0.22)
+	_mana_bar.add_theme_stylebox_override("background", mana_bg)
+	_hud_layer.add_child(_mana_bar)
 
 	_lbl_status = make_label.call(Vector2(20, 620), 20)
 	_lbl_status.modulate = Color.YELLOW
@@ -324,6 +338,9 @@ func _refresh_hud() -> void:
 	if _cm:
 		_lbl_deck.text = "[%s] %s" % [_cm.get_core_display(), str(_cm.get_deck_spell_ids())]
 	_lbl_statuses.text = tr("UI_STATUSES") % [StatusManager.get_active_count(), VFXManager.get_active_count()]
+	if _mana_bar:
+		_mana_bar.max_value = PlayerStats.mana_max
+		_mana_bar.value = PlayerStats.mana
 
 func _refresh_shop_ui() -> void:
 	for i in _shop_btns.size():