v0.1.18 — docs: fleet stack guide + crowd favorites

Docs release — no code changes

• New: PI-WITH-HERDR.md — the pi × Herdr × pi-open-agents fleet stack:
  • Advantages over tmux (workspace persistence, mouse-first UX, agent awareness)
  • Agent-to-agent awareness via socket integration (full_lifecycle_hook_authority)
  • 5-command tutorial + reference workstation setup (6 agents, one screen)
• README:
  • "Popular requests, already covered" table — ecosystem's most upvoted asks (AGENTS.md 👍336, skills standard 👍183, subagent tool restrictions 👍70) mapped to what's already here
  • Roadmap section: #8 permission inheritance, #9 hot-reload, #10 per-call model override, #11 parallel subagent limit
  • Catchy fleet-stack hook: 🐑 "Herd your agents" + "Run a fleet" section
• CONTRIBUTING.md: added earlier in this cycle — read before opening PRs/issues