Improve code quality and add status badges to README

[Malcolmnixon]

This pull request contains a mix of documentation improvements, codebase refactoring, and enhanced error handling. The most significant changes include the addition of project status badges to the README.md, improved error handling and user feedback throughout the UI event boundaries, refactoring of several view models to use public properties for data binding, and documentation clarifications for the file watcher subsystem. There are also minor code improvements for path handling and syntax highlighting safety.

Documentation and Project Metadata:

• Added GitHub and quality badges to the top of README.md and defined their references at the bottom for improved project visibility and status reporting. [1] [2]
• Clarified terminology and method descriptions in the file watcher subsystem documentation, replacing references to PendingChanges with "pending-change set" and updating method signatures and descriptions for accuracy. [1] [2] [3] [4] [5]

Error Handling and User Feedback:

• Added comprehensive, intentionally broad exception handling with explanatory comments to all major UI event boundaries (file/folder open, close all, drag-and-drop, and predefined view selection) to ensure user-facing error messages and prevent application crashes. [1] [2] [3] [4] [5]

ViewModel Refactoring for Data Binding:

• Changed several private fields in view models to public partial properties using [ObservableProperty] for improved data binding and testability in DiagnosticsToolViewModel, PredefinedViewsToolViewModel, and QueryDialogViewModel. [1] [2] [3]

Code Quality and Safety Improvements:

• Updated file path handling to use PathHelpers.SafePathCombine for safer path construction in application initialization and design-time shell factory. [1] [2]
• Added a bounded timeout to the regular expression used for keyword syntax highlighting to prevent catastrophic backtracking on user input.
• Added explanatory comments to reflection-based keyword extraction for maintainability and graceful degradation.

Other Minor Improvements:

• Refactored static/shared constants in AboutDialogViewModel and eliminated string literal duplication for license names. [1] [2]
• Minor corrections in dock layout initialization and event handler signatures. [1] [2]

These changes collectively improve project documentation, robustness, maintainability, and the user experience.