feat(team-mode): align member and lead prompts with Claude Code free-code reference

Bring the team member addendum and the team-mode skill in line with the
Claude Code experimental Agent Teams reference (../free-code) on the
behavioral framing the LLM needs, while keeping every omo-specific
constraint (TeamRunId param, lead-only tool blocklist, eligibility
registry, sisyphus-junior routing) intact.

Member addendum (src/features/team-mode/member-guidance.ts) — adopt
free-code teammatePromptAddendum.ts wisdom that was missing:

- "User interacts primarily with the team lead" — members no longer try
  to address the user directly; they coordinate via task system + DMs.
- Stronger emphasis that plain assistant text is invisible to the team;
  team_send_message is mandatory, not optional.
- Broadcast (`to: "*"`) called out explicitly with "sparingly" guidance
  and the lead-only constraint.
- "Idle is normal" section: idle ≠ done, idle teammates can still
  receive messages, the lead must not treat idle as an error.
- "Communication rules" section forbidding structured JSON status
  messages and forbidding terminal tools as a peer-inspection backdoor;
  always reference teammates by NAME, not session ID.
- Auto-delivery framing: messages arrive as new turns, no manual inbox
  polling, no need to quote a teammate's message back to the lead.

Team-mode skill (src/features/builtin-skills/skills/team-mode.ts) —
adopt free-code TeamCreateTool/prompt.ts sections that were missing:

- Task ownership: any agent can set/change `owner` via team_task_update.
- Automatic message delivery: <peer_message ...> envelope flow.
- Teammate idle state: idle is the expected post-turn state; peer DM
  summaries surface in the lead's idle notification.
- Discovering team members: team_status + ~/.omo/teams/ config; refer by
  name, never raw session IDs.
- Task list coordination: claim by ID order (lowest first), check after
  every completion, escalate blocking deadlocks to the lead.
- Communication rules: same anti-patterns as the member addendum, scoped
  for the lead's awareness (no JSON status, no terminal peer-inspection,
  no delegate-task from inside members).

Test (create.test.ts) updated to track the renamed section header
("Lead-only tools you must NOT call") and to lock the new free-code
parity assertions ("user interacts primarily with the team lead",
"Idle is normal", "structured JSON status messages").

All other contract tests (team-mode skill keyword/section tests,
member parser, runtime tests) untouched and still passing.

Generated with assistance of [OhMyOpenCode](https://github.com/code-yeongyu/oh-my-opencode).

src/features/team-mode/team-runtime/create.test.ts

@@ -150,12 +150,15 @@ describe("createTeamRun", () => {
     const firstPrompt = (launchMock.mock.calls as Array<[LaunchInput]>)[0]?.[0].prompt ?? ""
 
     // then
-    expect(firstPrompt).toContain("Do not call lead-only lifecycle tools")
+    expect(firstPrompt).toContain("Lead-only tools you must NOT call")
     expect(firstPrompt).not.toContain("3. Request shutdown via `team_shutdown_request`")
     expect(firstPrompt).toContain("Include `summary` and `references`")
     expect(firstPrompt).toContain("Move to `status: \"in_progress\"` when you start working")
-    expect(firstPrompt).toContain("delegate-task: Do not call this")
+    expect(firstPrompt).toContain("Do NOT call this from inside team members")
     expect(firstPrompt).toContain("lead can decide whether to request shutdown")
+    expect(firstPrompt).toContain("user interacts primarily with the team lead")
+    expect(firstPrompt).toContain("Idle is normal")
+    expect(firstPrompt).toContain("structured JSON status messages")
   })
 
   test("rolls back launched members in reverse order when a later spawn fails", async () => {