ci(release): list failed jobs in pre-release failure notifications #4718

User Story

As the triage engineer or release captain, I want a failed pre-release's Slack notification to link the failed jobs, so I can start on the fix without opening a 90-job run to find the problem.

Problem Statement

notify-prerelease-failure in .github/workflows/release-prerelease.yml posts the same text for every failure:

❌ OpenShell prerelease v0.1.5-pre.5 failed (attempt 1). Published artifacts remain available.
View failed release run

It doesn't say which job broke. For v0.1.5-pre.5 (run 39250333833), the cause was one Cargo Deny job among 92. In the triage thread, Drew suggested this format:

OpenShell v0.1.5-pre.5 release qualification failed.

Failing checks
• [Check Name](link to failing check)

Impact / Why This Matters

Pre-releases run every weekday and fail often for unrelated reasons: new RustSec advisories, runner flakes, registry errors. Linking the failed jobs in the message gets triage to the cause in one click.

Proposed Design

In notify-prerelease-failure, keep the existing message and append a "Failed jobs" list. It links every failure or timed_out job in the current run attempt, using the Actions jobs API (actions: read). If the lookup fails, send the message without the list.

Acceptance Criteria

• A failed pre-release notification links each failed job.
• The notification still sends when the jobs API call fails.
• CI.md mentions the job links.

Alternatives Considered

Using Slack Block Kit sections. The existing webhooks use plain text with mrkdwn, which supports the requested layout, so this keeps the change small.