feat(daemon): add github pr endpoints

[donbeave]

Summary

This stacks the third Desktop Agent Hub daemon slice on top of PR 306: the daemon now advertises and serves github/my_open_prs, github/project_inbox, and github/repository_prs so Desktop can render newest-first open PR inbox views through the versioned daemon protocol. The implementation uses the operator's existing gh authentication, parses structured JSON, sorts by creation time descending, and applies owner/repository filters without exposing tokens to Desktop.

What's deferred (follow-up PRs and risks)

• Previous PR in chain: PR 306 (feat(daemon): add workspace session discovery) must be reviewed after PR 283 and before this PR.
• Current slice: GitHub PR lookup endpoints, daemon capability advertisement, newest-first sorting, owner/repository filtering, and focused parser/filter tests.
• Next planned PR: Ghostty launch/open action contract for workspace/launch and desktop/open.
• Later planned PRs, in order: Claude/Codex/Amp account status endpoints, native macOS status bar, menu bar workspace counts, menu bar PR/project inbox, desktop window shell, Desktop PR/project filters, Desktop Workspaces and Running Agents views, then attention/ready-for-review notification routing.
• Review order: PR 283 first, PR 306 second, this PR third, then each downstream Desktop Agent Hub PR in sequence.
• Remaining risks: this is a live gh lookup path, not the later cache-first PR index; private repository visibility depends on the operator's gh scopes; Amp account status remains deferred; macOS app packaging and daemon version negotiation remain unvalidated until the SwiftUI/AppKit slices land.

Verify locally

Checkout

Paste this first to bypass the tirith paste scanner for the rest of the session:

export TIRITH=0

Then paste the checkout block:

mkdir -p "$HOME/Projects/jackin-project/test"
cd "$HOME/Projects/jackin-project/test"

if [ ! -d jackin/.git ]; then
  git clone https://github.com/jackin-project/jackin.git
fi

cd jackin
mise trust
git fetch -f origin jackin/desktop-github-pr-endpoints:refs/remotes/origin/jackin/desktop-github-pr-endpoints
git checkout -B jackin/desktop-github-pr-endpoints refs/remotes/origin/jackin/desktop-github-pr-endpoints

Static checks

cargo fmt --check
cargo clippy --lib -- -D warnings

Tests

cargo test --lib daemon::tests

The focused tests cover daemon capability advertisement, GitHub PR JSON parsing, newest-first sorting, owner/repository filtering, gh limit clamping, and the prior daemon protocol/session/workspace cases.

User smoke: daemon lifecycle

cargo run --bin jackin -- daemon restart
cargo run --bin jackin -- daemon status
cargo run --bin jackin -- console --debug

gh auth status should show the GitHub account/scopes the daemon will use for PR lookup requests.

Documentation

cd docs
bun install --frozen-lockfile
bun run dev

Astro serves at http://localhost:4321/. Pages to walk:

http://localhost:4321/reference/roadmap/jackin-daemon/
UPDATED roadmap page. Check the protocol capability table for the three GitHub PR methods and the Phase 3 note.

http://localhost:4321/reference/roadmap/jackin-desktop-agent-hub/
UPDATED roadmap page. Check the existing local foundation section for Desktop's daemon-backed PR lookup path.

Migration notes

None. These endpoints are additive and use the operator's existing gh login; no token storage or config migration is introduced.

[donbeave]

Closing this narrower slice because the daemon/Desktop Agent Hub work is now consolidated for broad review in #317.

[donbeave]

Superseded by #317, which carries the combined daemon/Desktop Agent Hub feature and links this PR in its consolidated trail.