Clarify live QA coordination guidance

[Ustice]

Summary

• Add coordinator-worktree guidance for substantial kanban sessions and compressed coordinator CONTEXT.md state.
• Add a single live-QA controller pattern for shared Timberborn sessions, launch/restart decisions, and retry ordering.
• Add assignment-packet fields for live-QA ownership, shared lock/process constraints, and startup diagnostics.
• Document startup failure taxonomy, self-matching process-check avoidance, fresh worktree bun install --frozen-lockfile, gh fallback, and shell-safe GitHub comments.
• Extend scripts/create-agent-worktree.ts help/template for coordinator worktrees.

Verification

• git diff --check passed.
• bun run typecheck passed before and after merging latest origin/main.

Notes

This incorporates the process reviewer commit d96bd956 plus the local coordinator-worktree guidance that was already in the main checkout.