feat(#1355): detect-and-warn guard for claude-code agent-teams (#1371)

* feat(#1355): detect-and-warn guard for claude-code agent-teams

GSD's multi-agent orchestration can stall under claude-code's experimental
agent-teams (a subagent's completion fails to route to the orchestrator). Per
the maintainer decision, the accepted scope is a read-only detector + one
non-fatal warning — NOT the declined run_in_background/TaskOutput conversion.

- New Teams Status Module (src/teams-status.cts → gsd-core/bin/lib/teams-status.cjs):
  pure resolveTeamsStatus({runtime, env}) + thin CLI cmdTeamsStatus reusing
  resolveRuntime. active = strictly-truthy env flag AND runtime === 'claude'.
- Wire `gsd-tools query teams-status [--active]` (read-only; no capability
  registration needed — conformance gates govern features, not query commands).
- One non-fatal warning in plan-phase.md before the first Agent spawn, gated on
  `query teams-status --active`; zero behavior change on non-claude/teams-off.
- Hermeticity: clear CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS in run-tests.cjs +
  SESSION_ENV_KEYS. Docs reference + CONTEXT.md glossary. Built lib gitignored.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* chore(#1355): add changeset for teams-detect guard

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* test(#1355): bump plan-phase.md workflow size baseline (+407B for teams warning)

The non-fatal agent-teams warning block added to plan-phase.md grew it
92759 → 93166 bytes, past its committed per-file baseline ratchet. The growth
is small, deliberate, and still well under the workflow tier hard cap. Regenerate
the baseline via `npm run size:baseline` (only plan-phase.md changed).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* chore(#1355): register teams-status.cjs in the inventory manifest

The new teams-status CLI module is a tracked surface; regenerate
docs/INVENTORY-MANIFEST.json (cli_modules family) via
gen-inventory-manifest.cjs --write so the inventory-manifest-sync gate passes.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

tests/active-workstream-store.unit.test.cjs

@@ -34,7 +34,7 @@ const SESSION_ENV_KEYS = [
   'GSD_SESSION_KEY', 'CODEX_THREAD_ID', 'CLAUDE_SESSION_ID', 'CLAUDE_CODE_SSE_PORT',
   'OPENCODE_SESSION_ID', 'GEMINI_SESSION_ID', 'CURSOR_SESSION_ID', 'WINDSURF_SESSION_ID',
   'TERM_SESSION_ID', 'WT_SESSION', 'TMUX_PANE', 'ZELLIJ_SESSION_NAME',
-  'TTY', 'SSH_TTY',
+  'TTY', 'SSH_TTY', 'CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS',
 ];
 
 function clearSessionEnv() {