Browser extension for github.com #52

Problem

Needly knows things GitHub does not: attention score, review risk, agent authorship, how long something has really been waiting, and what changed since you last looked. None of it is visible at the moment the developer is actually looking at the pull request.

Scope

A browser extension that injects Needly context into github.com.

• Attention score and review risk on the pull request page
• "What changed since you last looked" in the timeline
• Waiting duration on pull request list rows
• Archive and snooze from the pull request page
• Badge on the extension icon with the current attention count

Acceptance criteria

• Manifest V3, published for Chrome, Edge and Firefox
• Injected UI is visually distinct from GitHub's own, so it is never mistaken for a native feature
• Degrades silently when GitHub changes its DOM, rather than breaking the page
• Requests the narrowest host permissions that work, github.com only
• No page content is sent anywhere; the extension reads the Needly API and renders
• Can be disabled per repository

Notes

Lower priority than the check run work, which reaches every collaborator on a repository rather than only people who installed an extension.