docs(orchestrate): document coordinator permission requirements for the tmux substrate

[choiyounggi]

Docs-only. Field-hit gap: a fully prepared orchestration run stalled at its very first launch because the coordinator session ran in auto mode, and the permission classifier hard-flagged launch-session.sh … bypassPermissions as privilege escalation — the classifier cannot see the guardrails deny-net that makes the pattern safe, and nothing in the skill or README told the user this requirement exists.

• SKILL.md Preflight: new "Coordinator permissions (tmux substrate)" block — explains the classifier interaction, instructs a blocked coordinator to surface the snippet and STOP (never work around the block; an agent widening its own permissions is itself classifier-blocked by design), and carries the exact permissions.allow + autoMode.allow snippet for .claude/settings.local.json. safe-cleanup.sh is deliberately absent from the allowlist so destructive verbs keep their normal review. Notes that the path rules cover full-path invocations while the autoMode.allow rule covers variable-form ones, and that the same autoMode rule fixes the Orca substrate if its embedded flag is ever flagged.
• README.md / README.ko.md: a compact setup note in the Orca-integration section pointing at the SKILL.md snippet.

No script, test, or version changes.