Prefix-filtred prompt history navigation

[avillagran]

• Implement filtered history navigation (Ctrl/Cmd + Up/Down) in the prompt input
• Preserve normal history behavior when not filtering
• Add a lightweight, runtime-free test helper for prompt history to avoid importing Solid in - unit tests
• Update history store to delegate test factory to the helper
• Add unit tests for history navigation

Video: https://x.com/avillagran/status/2012382900499390659/video/1

[github-actions]

For keybind-related issues, please also check our pinned keybinds documentation: #4997