feat: Integrate gh-velocity for automated project metrics

[dvhthomas]

Summary

• Add four GitHub Actions workflows for automated velocity metrics using gh-velocity:
  • Weekly report (velocity-weekly.yml): Posts a Discussion every Monday at 09:00 UTC with 7-day project metrics
  • PR merge (velocity-pr.yml): Appends velocity metrics to PR body on merge, with idempotent sentinel markers
  • Issue close (velocity-issue.yml): Appends velocity metrics to issue body when closed as completed (skips "not planned")
  • Release (velocity-release.yml): Automatically posts release quality Discussion when a release is published
• Configuration auto-generated via gh velocity config preflight --write
• Removed all 6 legacy velocity bash scripts — fully replaced by gh-velocity
• Updated /release command Step 9 to note release metrics are now automated
• Updated SKILL.md and AGENTS.md to reference gh velocity commands

Key Design Decisions

• Sentinel markers (<!-- gh-velocity-start/end -->) ensure idempotent body edits on workflow re-runs
• Bot exclusion: dependabot PRs are excluded from metrics to avoid skewing averages
• State reason guard: Issue workflow only fires for completed closures, not "not planned"
• Preflight config: Used gh velocity config preflight --write for auto-generated, repo-aware configuration
• Full removal of legacy scripts: No fallback needed since gh-velocity is the canonical tool
• workflow_dispatch on all workflows for manual testing

Test plan

• Run gh velocity config validate (already passing locally)
• Trigger velocity-weekly.yml via workflow_dispatch and verify Discussion is created
• Trigger velocity-release.yml via workflow_dispatch with a tag and verify Discussion
• Merge a test PR and verify metrics are appended to PR body
• Close an issue as completed and verify metrics are appended to issue body
• Close an issue as "not planned" and verify no metrics are appended
• Re-run a workflow and verify sentinel markers prevent duplication

Post-Deploy Monitoring & Validation

• What to monitor: GitHub Actions workflow runs in the Actions tab
• Validation checks: gh run list --workflow=velocity-weekly.yml --limit=1
• Expected healthy behavior: Weekly Discussion posts appear, PR/issue bodies contain metrics blocks
• Failure signal: Workflow runs with red status; missing metrics blocks on merged PRs
• Validation window: First week after merge
• Owner: Repo maintainer

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🤖 Generated with Claude Opus 4.6 (1M context) via Claude Code

Metrics

Opened by @dvhthomas (agent-assisted) on 2026-03-21 14:38 UTC. Merged 2026-03-21 19:23 UTC.

Metric	Value
Cycle Time	4h 44m (created -> merged)
Time to First Review	n/a
Review Rounds	0

_{Generated by gh-velocity}

How to interpret

Command: gh velocity pr --post

Setting	Value
repository	CalcMark/go-calcmark