feat(agent-skill): give the codeman skill to every agent CLI, not just Claude

The agent skill only reached Claude Code: injection wrote
.claude/skills/codeman, which no other CLI reads, and the per-session
preamble was seeded for claude alone. A Codex, Gemini, OpenCode,
Antigravity, Grok, DeepSeek or OMP session inside Codeman never learned it
could start and drive workers.

- Registry field capabilities.agentSkillDir (a closed enum, since
  clis.json can set it and it decides where the server writes) names the
  skills directory each CLI scans. Claude keeps .claude/skills; those seven
  CLIs get the same skill in <case>/.agents/skills/codeman (each measured to
  scan it; Claude Code does not, so it never sees two copies). pi gets none:
  a project skill makes pi ask "Trust project folder?" at startup.
- The preamble is seeded for every local session whose CLI takes the
  skill; nothing in it is claude-specific.
- The skill text is CLI-neutral and names the two CLI-side failures to
  report instead of retrying: a sandbox that blocks loopback (Codex's
  default), and commands that do not carry this session's environment
  (Codex 0.162 runs them in a shared app-server daemon).
- POST /api/sessions injects after the launch pre-flight, so a CLI that
  cannot start leaves nothing in the workspace.
- codeman skill install gains --mode; uninstall --case removes the copy
  from every directory the registry can write.
- The settings toggle moves to Agents & CLIs > All agent CLIs.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

docs/extending-codeman.md

@@ -163,9 +163,10 @@ respawn, Ralph, the orchestrator, search, and admin. Each route module carries a
 If the caller is an agent running _inside_ a Codeman session, install the packaged
 agent skill instead of teaching it these calls by hand: `skills/codeman` in the repo
 (`npx skills add Ark0N/Codeman --skill codeman -g`, or `codeman skill install
-[--case <name>]`, or the synced `agentSkillEnabled` App Setting for automatic
-per-case injection on Claude session create). The skill carries the guard, the
-safety rules, and verified wait/orchestration recipes.
+[--case <name>] [--mode <mode>]`, or the synced `agentSkillEnabled` App Setting for
+automatic per-case injection on session create, into the directory each CLI scans for
+skills). The skill carries the guard, the safety rules, and verified
+wait/orchestration recipes.
 
 The common ones: