fix(desktop): rename to Harper

[elijah-potter]

Issues

N/A

Description

Renames the Tauri desktop product from harper-desktop to Harper so future macOS DMGs contain Harper.app instead of harper-desktop.app.

Also updates the website download and desktop updater asset lookup logic to handle the new artifact names while preserving compatibility with previously published harper-desktop artifacts.

Demo

N/A

How Has This Been Tested?

N/A

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

• I made up the sentences in the unit tests.
• The sentences in the unit tests were generated by an AI.
• I'm using examples from the bug report / feature request.
• I collected real-world sentences for the unit tests.

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.