feat(draw): add collaborative Excalidraw plugin with real-time collab

Add `crab draw` command as a new plugin that launches an Excalidraw canvas
with real-time collaboration via Socket.IO and tunnel sharing (cloudflared/ngrok/bore).

Features:
- Start/reopen/list/delete drawing sessions saved to .crab/draw/
- Real-time multi-user collaboration with cursor sync
- Tunnel support for sharing sessions with remote teammates
- Session prefix matching with interactive disambiguation prompt
- Autosave every 30s, final save on Ctrl-C
- Drawing artifacts commit to git for team sharing

Bump version to 0.11.0.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: MrFlounder

.gitignore

@@ -25,3 +25,6 @@ Thumbs.db
 # Test artifacts
 test-output/
 coverage/
+
+# Shared local volume (crabcode)
+.local

.release-please-manifest.json

@@ -1,3 +1,3 @@
 {
-  ".": "0.10.1"
+  ".": "0.11.0"
 }

plugins/draw/.gitignore

@@ -0,0 +1,4 @@
+node_modules/
+dist/
+ui/node_modules/
+ui/dist/

plugins/draw/bin/crab-draw.js

@@ -0,0 +1,2 @@
+#!/usr/bin/env node
+import '../dist/cli.js';