Add /prerelease slash command

[nanotaboada]

Problem

There is no /prerelease slash command for this repo. The release process
(determining the next version and club codename, preparing the release
branch, updating CHANGELOG.md, tagging) is done manually and is
error-prone.

Additionally, step 1 of /precommit currently reads:

"Remind me to update CHANGELOG.md [Unreleased] section (Added /
Changed / Fixed / Removed) — I must do this manually."

The agent should handle this step, not defer it to the user.

Proposed Solution

1. Update step 1 of .claude/commands/precommit.md to:

   Update CHANGELOG.md [Unreleased] section — add an entry under the
   appropriate subsection (Added / Changed / Fixed / Removed) describing
   the changes made, referencing the issue number.

2. Add .claude/commands/prerelease.md implementing a three-phase
   pre-release checklist:

   • Phase 1 — Determine next release: verify clean master, read the
     historic football club naming convention from CHANGELOG.md (A–Z table),
     run git tag --sort=-v:refname, infer the version bump from
     [Unreleased], and present a summary for confirmation before proceeding.
   • Phase 2 — Prepare release branch: create release/vX.Y.Z-{club},
     move [Unreleased] content into a versioned heading, propose the
     docs(changelog) commit, then run /precommit and open a PR — all with
     explicit confirmation at each step.
   • Phase 3 — Tag and release: wait for CI, CodeRabbit, and merge
     confirmation; pull master; propose the annotated tag; push only after
     explicit approval.

Acceptance Criteria

• Step 1 of /precommit updates CHANGELOG.md automatically, referencing
  the issue number
• /prerelease is available and follows the propose-before-acting workflow
• Correctly reads the club naming convention from CHANGELOG.md
• Infers the correct version bump from [Unreleased] content

[coderabbitai]

🔗 Related PRs

#284 - chore(claude): improve Claude Code integration [merged]
#287 - ci(release): implement named releases with tag-based deployment (#252) [merged]
#291 - docs(changelog): prepare release notes for v1.0.0-arsenal [merged]

---

📝 Issue Planner

_{Check the box below or use the @coderabbitai plan command to generate an implementation plan and prompts that you can use with your favorite coding assistant.}

• Create Plan

---

🧪 Issue enrichment is currently in open beta.

You can configure auto-planning by selecting labels in the issue_enrichment configuration.

To disable automatic issue enrichment, add the following to your .coderabbit.yaml:

issue_enrichment:
  auto_enrich:
    enabled: false

💬 Have feedback or questions? Drop into our discord!