docs: consolidated genie capabilities reference

[namastex888]

Summary

Genie's capabilities (spawn flags, agent resolution order, multi-agent patterns, orchestration commands) are documented but scattered across multiple files in the genie repo:

• skills/genie/SKILL.md — agent directory, resolution order
• docs/CO-ORCHESTRATION-GUIDE.md — worktree isolation, multi-agent patterns
• Source code — spawn flags (--session, --cwd, --model, --skill, --layout, etc.)

Users and agents need a single consolidated reference page on the docs site.

Proposed content

1. Genie CLI Reference — all commands with flags and examples
2. Agent Orchestration Guide — spawn, monitor, send, resume lifecycle
3. Multi-Agent Patterns — team creation, concurrent dispatch, worktree isolation
4. Spawn Flags Cheat Sheet — --session, --cwd, --model, --skill, --color, --plan-mode, --permission-mode, --extra-args, --no-auto-resume

Source material

• automagik-dev/genie repo: skills/genie/SKILL.md, docs/CO-ORCHESTRATION-GUIDE.md, src/genie.ts (CLI definitions)

Originated from triage of genie#724.