feat(desktop): add report issue buttons to menus

[elijah-potter]

Issues

None.

Description

Adds a native "Report an Issue" entry to Harper Desktop menus:

• Adds the item to the tray/menu-bar menu alongside Settings and Quit.
• Adds the item to the native Help menu.
• Wires both entries to open Harper's GitHub issue-report URL in the default browser.

Demo

Not included.

How Has This Been Tested?

Not applicable; this change only adds menu items and URL-opening wiring.

AI Disclosure

• I am a human and didn't use any AI.
• I used LLM features of my editor, but not an agent.
• I used an AI agent interactively.
• I am an agent or I got an agent to do the work autonomously.

If Your PR Implements or Enhances a Linter

Not applicable.

Checklist

• I have performed a self-review of my own code
• I have added tests to cover my changes
• I have considered splitting this into smaller pull requests.