fix: multiple community-reported issues

- feat(plugin.json): add agents declaration to make 9 agents visible
  in /agents command (fixes #66, closes PR #67)

- fix(backend-patterns): correct requirePermission HOF pattern to
  properly wrap handlers instead of expecting Request directly
  (fixes #54, closes PR #63)

- docs(user-CLAUDE): add privacy guideline about redacting secrets
  from logs before sharing (fixes #38, closes PR #39)

- fix(eval-harness): add mandatory frontmatter with name, description,
  and tools fields (closes PR #58)

.claude-plugin/plugin.json

@@ -22,6 +22,7 @@
     "automation",
     "best-practices"
   ],
+  "agents": "./agents",
   "commands": "./commands",
   "skills": "./skills"
 }