Update for Dynamic Plugin Pages and Settings Hub Integration

[mdwigley]

Task Description

Enhance the application’s dependency injection setup and MainViewModel logic to support dynamic discovery and navigation of plugin-contributed pages, as well as seamless integration of the consolidated settings hub (including the plugin manager). This will ensure that:

• Plugin pages are correctly injected, registered, and displayed in the navigation menu at runtime.
• The SettingsView and SettingsPluginsView are permanently available in navigation as part of the settings hub.
• Navigation actions seamlessly switch between plugin pages and the settings hub without errors or conflicts.
  The outcome is a consistent and extensible navigation system that dynamically adapts to plugins and always provides a unified settings hub entry.

Acceptance Criteria

• Dependency injection registers SettingsView, SettingsViewModel, SettingsPluginsView, and SettingsPluginsViewModel with the service provider.
• MainViewModel maintains a dynamic collection (MainPageItems) that includes both core app pages and plugin-contributed pages at runtime.
• A permanent "Settings" entry exists in the navigation that opens the consolidated settings hub (with plugin manager included).
• Selecting any plugin page updates the displayed main content to the correct view and viewmodel.
• Navigation gracefully handles missing or invalid plugin pages without breaking the app.

Steps to Complete

• Update App.axaml.cs to register SettingsView and SettingsViewModel in the DI container.
• Update Bootstrapper to register SettingsPluginsView and SettingsPluginsViewModel.
• Extend MainViewModel to maintain a permanent settings entry and support dynamic injection of plugin-provided pages.
• Implement navigation logic to switch to the settings hub when "Settings" is selected.
• Ensure plugin page descriptors are properly resolved, instantiated, and added to the navigation menu.

Stakeholders / Reviewers

• PlugHub Core Engineering Team
• Plugin Developers
• End Users

Dependencies / Blockers

• Depends on: Develop and Integrate Plugin Management UI in Settings Hub #71
• Blocks: Implement Error Handling and Fallback Strategies for Plugin Resource Integration #73