feat: show repository-host PR and issue context in the changes pane

[nonlooped]

Summary

• Show the GitHub/GitLab PR (or MR) associated with the current branch in the Changes pane: title, state, author, description, review comments, checks, linked issues, and base-branch comparison (ahead/behind + changed files).
• Falls back to a branch-name issue number lookup when no PR/MR exists yet; shows nothing when neither is found.
• Reads through the user's existing gh/glab CLI authentication; NativePi makes no GitHub/GitLab API calls of its own.
• "Open in browser" opens the PR/MR or a linked issue. Comments can be explicitly inserted into the composer one at a time; nothing is auto-injected into Pi.

Test plan

• bun run typecheck
• bun run test (163 pass)
• bun run build
• Manual verification in a running window (not performed; AGENTS.md disallows starting a dev server without being asked)

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
nativepi	Ignored	Preview	Jul 31, 2026 10:13am

[chatgpt-codex-connector]

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