feat(pilot): Phase 7 — polish (loading/empty states, shortcuts, responsive drawer)

- WhatWeKnow shows a "synthesizing" indicator + skeleton pulse while the
  chat cycle is in-flight; task-lane header mirrors the signal with a
  "thinking" pip so engineers know the AI is still working.
- Quiet-state hint when the lane is open (facts exist) but no open
  questions, checks, or active fix — keeps the surface from looking
  "finished" when the AI is about to follow up.
- Keyboard shortcuts: ⌘↵/Ctrl+↵ send in the composer (plain Enter still
  sends), ⌘G toggles the Script Generator panel for the active fix,
  `?` opens a new ShortcutsHelpOverlay listing all bindings. ⌘K palette
  was already wired in TopBar.
- Responsive: below 1200px the task lane collapses to a bottom drawer
  with a backdrop + a floating "Tasks ●" toggle button. TaskLane now
  takes a `variant: 'side' | 'drawer'` prop; drawer variant drops the
  resize handle and uses the shared slide-in-bottom animation.
- Build hygiene: fixed a pre-existing TS error in confirm-post error
  handling (duplicate `response` type keys) and an unused-import warning
  in TemplatizePrompt.

Verified: `npx tsc -b` and `npm run build` both clean against the dev
stack; Vite HMR applied each change without errors.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/components/pilot/script/TemplatizePrompt.tsx

@@ -20,7 +20,7 @@
  * modal for the next one after save/skip.
  */
 import { useEffect, useMemo, useState } from 'react'
-import { Loader2, Check, X, Trash2, Sparkles } from 'lucide-react'
+import { Loader2, Check, Trash2, Sparkles } from 'lucide-react'
 import { cn } from '@/lib/utils'
 import { Modal } from '@/components/common/Modal'
 import { toast } from '@/lib/toast'