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>

sh/e2e/lib/common.sh

@@ -5,7 +5,7 @@ set -eo pipefail
 # ---------------------------------------------------------------------------
 # Constants
 # ---------------------------------------------------------------------------
-ALL_AGENTS="claude openclaw zeroclaw codex opencode kilocode hermes junie cursor"
+ALL_AGENTS="claude openclaw codex opencode kilocode hermes junie cursor"
 PROVISION_TIMEOUT="${PROVISION_TIMEOUT:-720}"
 INSTALL_WAIT="${INSTALL_WAIT:-600}"
 INPUT_TEST_TIMEOUT="${INPUT_TEST_TIMEOUT:-120}"