refactor: support DMS 1.5.0+ composite plugin model

[hthienloc]

Refactor the plugin to use the new composite plugin model introduced in DMS 1.5.0.

Current Hacky Pattern

• Uses type: "daemon" with capabilities: ["control-center"].
• Uses readonly property bool isDaemonInstance: root.parent !== null in QuickCaptureWidget.qml because the component gets loaded multiple times (once as daemon, once as widget).
• Relies on PluginService.pluginInstances["quickCapture"] to delegate capture events from widget to the daemon.

Planned Changes

• Update plugin.json to:

  "type": "composite",
  "components": {
      "daemon": "./QuickCaptureDaemon.qml",
      "widget": "./QuickCaptureWidget.qml"
  },
  "requires_dms": ">=1.5.0"

• Create QuickCaptureDaemon.qml to handle background timers, process executions, and screenshot controls.
• Keep QuickCaptureWidget.qml strictly for UI elements, calling the daemon functions directly.