add plugin settings, per-tile refresh, settings menu, touch-friendly UI

- Plugin settings infrastructure in PluginManager with config/plugin_settings.cfg
  storage, manifest [settings] sections, CRUD API, plugin_setting_changed signal
- Per-tile refresh intervals: 100ms base tick, per-tile update_interval_ms
  metadata, dynamic tween durations clamped to refresh window
- Settings menu (PopupPanel) with General/Plugins/About tabs, plugin
  activation toggles, per-plugin settings cog buttons
- Plugin settings popup (PopupPanel) with dynamic UI from setting definitions
  (SpinBox/CheckBox/LineEdit), auto-save on change
- Modal behavior: exclusive = true on settings windows
- Touch-friendly sizing: enlarged close buttons, cog buttons, controls, spacing
- Red corner close button redesign with rounded corners, hover/pressed states
- Split system_monitor into local_system_monitor (CPU, Memory) and test plugins
- Plugin activation/deactivation with layout preservation

plugins/test/plugin.cfg

@@ -0,0 +1,30 @@
+[plugin]
+name="Test"
+version="0.1.0"
+description="Development testing tiles and framework experiments"
+author="Fifthdread"
+
+[tiles]
+count=1
+
+[tile_0]
+id="testing"
+name="Testing"
+scene="res://plugins/test/tiles/testing/testing_tile.tscn"
+min_w=1
+min_h=1
+max_w=4
+max_h=4
+default_w=1
+default_h=1
+
+[settings]
+count=1
+
+[setting_0]
+key="testing_update_interval_ms"
+label="Testing Update Interval"
+type="int"
+default=1000
+min=100
+max=60000

plugins/test/tiles/testing/testing_tile.gd

@@ -0,0 +1,67 @@
+extends PluginTile
+
+
+@onready var title_label: Label = %Title
+@onready var label: Label = %Label
+@onready var vial_fill: ColorRect = %VialFill
+
+var _displayed_fill: float = 0.0
+var _fill_tween: Tween
+var _cycle: int = 0
+var _levels: Array[float] = [0.0, 0.25, 0.50, 0.75, 1.0]
+
+
+func initialize() -> void:
+	module_title = "Testing"
+	_setup_shader()
+	_style()
+
+
+func refresh(data: Dictionary) -> void:
+	_cycle = (_cycle + 1) % _levels.size()
+	var target: float = _levels[_cycle]
+
+	label.text = "%d%%" % roundi(target * 100.0)
+
+	# Clamp duration so animation never outlasts the refresh interval
+	var update_ms: int = data.get("update_interval_ms", 1000)
+	var duration: float = minf(0.6, update_ms / 1500.0)
+	if _fill_tween and _fill_tween.is_valid():
+		_fill_tween.kill()
+	_fill_tween = create_tween()
+	_fill_tween.tween_method(_set_fill, _displayed_fill, target, duration).set_ease(Tween.EASE_OUT).set_trans(Tween.TRANS_CUBIC)
+
+
+func _set_fill(value: float) -> void:
+	_displayed_fill = value
+	var mat := vial_fill.material as ShaderMaterial
+	if mat:
+		mat.set_shader_parameter("fill", value)
+
+
+func _setup_shader() -> void:
+	var mat := ShaderMaterial.new()
+	mat.shader = preload("res://shaders/vial_fill.gdshader")
+	mat.set_shader_parameter("liquid_color", Color(0.6, 0.3, 0.8, 1.0))
+	mat.set_shader_parameter("fill", 0.0)
+	mat.set_shader_parameter("noise_tex", load("res://assets/textures/noise_100.png"))
+	vial_fill.material = mat
+
+
+func _style() -> void:
+	var panel := StyleBoxFlat.new()
+	panel.bg_color = Color.TRANSPARENT
+	panel.corner_radius_top_left = 12
+	panel.corner_radius_top_right = 12
+	panel.corner_radius_bottom_right = 12
+	panel.corner_radius_bottom_left = 12
+	add_theme_stylebox_override("panel", panel)
+	add_theme_stylebox_override("panel_focused", panel)
+
+	title_label.add_theme_color_override("font_color", Color(0.7, 0.7, 0.8, 1.0))
+	title_label.add_theme_constant_override("outline_size", 2)
+	title_label.add_theme_color_override("font_outline_color", Color(0.0, 0.0, 0.0, 0.5))
+	label.add_theme_color_override("font_color", Color(0.9, 0.9, 1.0, 1.0))
+	label.add_theme_font_size_override("font_size", 48)
+	label.add_theme_constant_override("outline_size", 3)
+	label.add_theme_color_override("font_outline_color", Color(0.0, 0.0, 0.0, 0.7))

plugins/test/tiles/testing/testing_tile.tscn

@@ -0,0 +1,41 @@
+[gd_scene format=3]
+
+[ext_resource type="Script" path="res://plugins/test/tiles/testing/testing_tile.gd" id="1"]
+[ext_resource type="Shader" path="res://shaders/vial_fill.gdshader" id="2"]
+
+[node name="TestingTile" type="PanelContainer"]
+anchors_preset = 0
+script = ExtResource("1")
+
+[node name="VialFill" type="ColorRect" parent="."]
+unique_name_in_owner = true
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+mouse_filter = 2
+
+[node name="MarginContainer" type="MarginContainer" parent="."]
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+theme_constant_overrides/margin_left = 12
+theme_constant_overrides/margin_top = 12
+theme_constant_overrides/margin_right = 12
+theme_constant_overrides/margin_bottom = 12
+
+[node name="VBoxContainer" type="VBoxContainer" parent="MarginContainer"]
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+
+[node name="Title" type="Label" parent="MarginContainer/VBoxContainer"]
+unique_name_in_owner = true
+text = "Testing"
+
+[node name="Spacer" type="Control" parent="MarginContainer/VBoxContainer"]
+size_flags_vertical = 3
+
+[node name="Label" type="Label" parent="MarginContainer/VBoxContainer"]
+unique_name_in_owner = true
+horizontal_alignment = 1
+size_flags_horizontal = 4