fix(docs): rewrite cross-skill SKILL.md links so Docs Deploy build passes

[arnaudlh]

Fixes the failed Git-Ape: Docs Deploy run on main (run 27131977843).

Problem

After #142 merged, the Docusaurus production build failed with broken-markdown-link errors. Generated agent and skill pages still contained relative SKILL.md cross-references that do not exist in the rendered site, e.g.:

• docs/agents/azure-resource-deployer.md → ../skills/prereq-check/SKILL.md
• docs/agents/azure-template-generator.md → ../skills/azure-rest-api-reference/SKILL.md
• docs/skills/azure-stack-deploy.md → ../azure-stack-destroy/SKILL.md
• docs/skills/azure-stack-destroy.md → ../azure-stack-deploy/SKILL.md

scripts/generate-docs.js already rewrote sibling .agent.md links and skill scripts//references/ links, but never handled cross-references to other skills' SKILL.md files, so Docusaurus (onBrokenMarkdownLinks: throw) aborted the build.

Fix

• Add rewriteSkillRefLinks(body, targetBase) to the generator. It rewrites any [label](.../<skill>/SKILL.md) link to the docusaurus slug: ../skills/<slug> from agent pages, ./<slug> from skill pages.
• Wire it into both agent and skill body processing.
• Regenerate docs.

Validation

• node scripts/generate-docs.js — clean
• npm run build (with DOCUSAURUS_BASE_URL=/) — [SUCCESS] Generated static files, no broken-link errors
• Repo-wide grep confirms zero remaining relative SKILL.md links in website/docs/

Note

This PR also regenerates website/docs/workflows/git-ape-release.md, which had drifted from its source workflow after #144 (the generated doc was not refreshed at the time). Regeneration brings it back in sync with .github/workflows/git-ape-release.yml.

[sendtoshailesh]

Reviewed the generator change and regenerated docs end to end.

• rewriteSkillRefLinks() matches the broken cross-skill SKILL.md link shapes used today (../skills/<name>/SKILL.md from agents and ../<name>/SKILL.md from skills), derives the slug from the skill directory, and emits the correct Docusaurus-relative targets (../skills/<slug> vs ./<slug>).
• The change is wired into both agent and skill body processing without disturbing the existing .agent.md and scripts/ / references/ rewrites.
• I validated on the PR head by running node scripts/generate-docs.js and DOCUSAURUS_BASE_URL=/ npm --prefix website run build; the build succeeds. I also checked the generated docs for leftover markdown links to SKILL.md, .agent.md, or relative scripts/ / references/ targets and didn't find any unresolved cases.
• The git-ape-release.md regeneration lines up with the current workflow and looks like legitimate drift correction rather than an accidental doc edit.

I did not find any blocking issues. The only future edge case I can think of would be SKILL.md links that include anchors or query strings, but none of the current sources use that pattern, so this PR looks merge-ready for the stated fix.