docs: add complete features guide and rewrite LAN Pipes docs (#246)

- Add docs/features/all-features-guide.md — comprehensive guide covering
  all 18 features across 13 PRs (Buddy, Remote Control, Voice, Chrome,
  Computer Use, GrowthBook, Ultraplan, Daemon, Pipe IPC, LAN Pipes,
  Monitor, Workflow, Coordinator, Proactive, History/Snip, Fork, etc.)

- Rewrite docs/features/lan-pipes.md — user-facing guide with step-by-step
  quickstart, firewall config (Windows/macOS/Linux), command reference,
  keyboard shortcuts, routing modes, permission forwarding, FAQ

- Rewrite docs/features/lan-pipes-implementation.md — developer reference
  with updated architecture (hook extraction, ndjsonFramer, module singletons),
  corrected code references, NDJSON protocol spec, attach flow sequence

Co-authored-by: unraid <local@unraid.local>

Author: amDosion