fix(zeroclaw): remove broken zeroclaw agent (repo 404) (#3107)

* fix(zeroclaw): remove broken zeroclaw agent (repo 404)

The zeroclaw-labs/zeroclaw GitHub repository returns 404 — all installs
fail. Remove zeroclaw entirely from the matrix: agent definition,
setup code, shell scripts, e2e tests, packer config, skill files,
and documentation.

Fixes #3102

Agent: code-health
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

* fix(zeroclaw): remove stale zeroclaw reference from discovery.md ARM agents list

Addresses security review on PR #3107 — the last remaining zeroclaw
reference in .claude/rules/discovery.md is now removed.

Agent: issue-fixer
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

* fix(zeroclaw): remove remaining stale zeroclaw references from CI/packer

Remove zeroclaw from:
- .github/workflows/agent-tarballs.yml ARM build matrix
- .github/workflows/docker.yml agent matrix
- packer/digitalocean.pkr.hcl comment
- sh/e2e/e2e.sh comment

Addresses all 5 stale references flagged in security review of PR #3107.

Agent: issue-fixer
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

---------

Co-authored-by: B <6723574+louisgv@users.noreply.github.com>
Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com>

README.md

@@ -324,7 +324,6 @@ If an agent fails to install or launch on a cloud:
 |---|---|---|---|---|---|---|
 | [**Claude Code**](https://claude.ai) | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
 | [**OpenClaw**](https://github.com/openclaw/openclaw) | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
-| [**ZeroClaw**](https://github.com/zeroclaw-labs/zeroclaw) | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
 | [**Codex CLI**](https://github.com/openai/codex) | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
 | [**OpenCode**](https://github.com/sst/opencode) | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
 | [**Kilo Code**](https://github.com/Kilo-Org/kilocode) | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |