fix: remove stray heredoc artifact and quote YAML description field

[wali-reheman]

Summary

Two small fixes:

1. SECURITY.md: Remove trailing literal text EOFcat SECURITY.md (heredoc terminator that leaked into the file during PR docs: add SECURITY.md policy #410). Fixes stray EOFcat heredoc artifact at end of SECURITY.md #530.
2. specialized/zk-steward.md: Quote the description YAML field to fix parse error caused by colons in the description text. Fixes Frontmatter of zk-steward has YAML syntax issue #473.

Changes

• SECURITY.md: removed line 31 (the stray EOFcat SECURITY.md heredoc artifact)
• specialized/zk-steward.md: wrapped description value in double quotes

Verification

# YAML validation - should exit cleanly
python3 -c "import yaml; yaml.safe_load(open('specialized/zk-steward.md').read().split('---')[2])"

# SECURITY.md should end with the prompt injection reporting line, no trailing artifact
tail -1 SECURITY.md
# Expected: "- Report suspicious agent definitions that attempt prompt injection"

[bensl84]

Closing — this is my personal fork (bensl84/agency-agents). The canonical project lives at https://github.com/msitarzewski/agency-agents — please re-open your PR there. Thanks!