fix(insights): a11y + UX Pro Max audit — accessible list view, reduced-motion, focus, lazy-load

Accessibility (CRITIQUE per UI/UX Pro Max skill):
- NetworkGraph Accessibility Grade D → added accessible List view alternative
  (toggle Graph/List with cluster→notes table, keyboard navigable)
- aria-label text summary on graph container for screen readers
- role=button + tabIndex + onKeyDown on bridge note cards (keyboard accessible)
- focus-visible:ring on all interactive cards (isolated clusters, bridges, list items)

UX (HIGH):
- prefers-reduced-motion: whileHover disabled when user prefers reduced motion
- cursor-pointer verified + focus-visible:ring-ochre on all clickable cards
- Mobile sidebar: hamburger Menu button in header (dispatches open-mobile-sidebar)

Performance (MEDIUM):
- NetworkGraph lazy-loaded via next/dynamic (D3 ~200KB deferred, ssr:false)
- Loading spinner shown while D3 chunk loads

i18n:
- listView, graphAriaLabel, listAriaLabel added to 15 locales

.cursor/hooks/state/continual-learning.json

@@ -1,8 +1,8 @@
 {
   "version": 1,
   "lastRunAtMs": 1782633053032,
-  "turnsSinceLastRun": 1,
+  "turnsSinceLastRun": 6,
   "lastTranscriptMtimeMs": 1782633052959.9294,
-  "lastProcessedGenerationId": "17310ec7-5a0e-406b-a1a4-75a7c0439ee3",
+  "lastProcessedGenerationId": "fa1ae817-7a99-4fd6-8b50-8407600557dd",
   "trialStartedAtMs": null
 }