[Improve] Show all linked pull requests in task surfaces

[roomote-roomote]

Opened on behalf of Daniel Riccio. Follow up by mentioning @roomote-roomote, in the web UI, or in Slack.

What changed

Task workspace headers and Task Info now render every linked pull request with its canonical URL. Slack thread and automation footers now expose all active linked PRs instead of selecting one. Automation footer actions use unique IDs and stay within Slack's actions-block limit.

Why this change was made

Tasks can span multiple repositories and pull requests. Showing only the first or latest PR hid part of the work and made multi-PR tasks difficult to review.

Impact

Users can see and open the complete active PR set from the existing task surfaces, while compact task-list badges retain their existing behavior. Provider-specific PR URLs are preserved, and multi-PR automation footers remain valid Slack blocks.

Related PRs

• Demo seed data for single-PR and multi-PR tasks

Validation

Targeted web, communication, and Slack tests pass, including regression coverage for unique automation action IDs and the 24-PR cap. API, SDK, Slack, and web typechecks pass. Full visual proof remains unavailable because the proof runtime could not capture the seeded multi-PR state. The server-backed SDK router test also requires the unavailable test database.

[roomote-community]

No code issues found. See task

• packages/slack/src/automation-root-footer.ts:28 Reused Slack action IDs make multi-PR automation footers invalid.
• packages/slack/src/automation-root-footer.ts:25 Too many PR buttons can exceed Slack's 25-element actions-block limit.

_{Reviewed 6d1dc65}

[roomote-roomote]

Addressed both unresolved Slack automation-footer comments in commit 6d1dc655: PR action IDs are unique per button, and the PR button list is capped at 24 to preserve Slack's 25-element actions-block limit alongside Go to task. Added regression tests; Slack tests and typecheck pass.