Add live variant mode: element picker, action panel, poll/reply bridge (22 commands)

New feature: /impeccable live starts an interactive visual iteration server.
Users select elements in the browser, pick a design action (bolder, quieter,
etc.), and the agent generates HTML+CSS variants written directly to source.
The dev server's HMR hot-swaps them in, and MutationObserver progressively
reveals each variant in a cycler UI as it arrives.

Architecture:
- src/live/server.mjs: HTTP + WebSocket server with session token auth,
  long-poll /poll endpoint for the agent, WebSocket for the browser
- src/live/poll.mjs: CLI client (npx impeccable poll / poll --reply)
- src/live/browser.js: element picker with keyboard nav (arrows=siblings,
  shift+arrows=parent/child), action panel (12 commands, freeform input,
  variant count), variant cycler with progressive reveal via MutationObserver
- src/live/protocol.mjs: shared message types and event validation
- source/skills/impeccable/reference/live.md: agent loop instructions
  (inject script, poll loop, generate variants, accept/discard, cleanup)

CLI changes:
- bin/cli.js: added "poll" top-level command
- src/detect-antipatterns.mjs: liveCli() now delegates to src/live/server.mjs
- package.json: added ws dependency

Registered /impeccable live as command #22 across all standard locations.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.claude-plugin/plugin.json

@@ -1,6 +1,6 @@
 {
   "name": "impeccable",
-  "description": "Design fluency for frontend development. 1 skill with 21 commands (/impeccable polish, /impeccable audit, /impeccable critique, etc.) and curated anti-pattern detection.",
+  "description": "Design fluency for frontend development. 1 skill with 22 commands (/impeccable polish, /impeccable audit, /impeccable critique, etc.) and curated anti-pattern detection.",
   "version": "3.0.0",
   "author": {
     "name": "Paul Bakaus",