Phase 6: polish — error boundaries, a11y, smoke test doc

Close out the read-only surface before cutover with three families of
small fixes that the previous phases left unfinished:

- Error boundaries: add src/app/error.tsx (route-segment), global-error.tsx
  (root crash fallback with its own minimal html/body — no Providers
  dependency since those may be the thing that crashed), and not-found.tsx
  for a Hebrew 404 instead of the default Next page.

- Accessibility: wire usePathname() into AppShell so the current nav item
  gets aria-current="page" and a gold underline. Add aria-label + aria-hidden
  on the icon-only buttons that Phase 5 left text-less (corpus trash,
  parties-field Plus). Nav gets an aria-label of its own.

- Metadata template: title on each route now reads "X · עוזר משפטי" via
  the layout.tsx title.template. Description localized to Jerusalem.

- README: full E2E smoke test checklist covering all 9 screens, plus a
  backend contract table so future phases know which hook wraps which
  endpoint. Documents the known Gitea→Coolify webhook issue.

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

.taskmaster/tasks/tasks.json

@@ -848,13 +848,13 @@
         "description": "Port the remaining 5 views. Use TanStack Table for training corpus and diagnostics lists. Port any charts/visualizations from current index.html. Plan: ~/.claude/plans/joyful-marinating-sutton.md.",
         "details": "See full plan at ~/.claude/plans/joyful-marinating-sutton.md for architecture, critical files, risks, and open questions. This task is phase 5 of 7 in the legal-ai UI rewrite from vanilla HTML to Next.js 15 + shadcn/ui.",
         "testStrategy": "Feature parity with old legal-ai/web/static/index.html across all 10 views.",
-        "status": "in-progress",
+        "status": "done",
         "dependencies": [
           "86"
         ],
         "priority": "medium",
         "subtasks": [],
-        "updatedAt": "2026-04-11T17:28:06.562Z"
+        "updatedAt": "2026-04-11T17:33:42.976Z"
       },
       {
         "id": "88",
@@ -862,12 +862,13 @@
         "description": "Accessibility pass (keyboard nav, aria-label on RTL icons, focus trap in modals). Error boundaries + toast notifications for failed mutations. Loading states for every query. Cross-browser smoke test (Chrome, Firefox, Safari) + mobile device test. Document E2E smoke test script in web-ui/README.md. Plan: ~/.claude/plans/joyful-marinating-sutton.md.",
         "details": "See full plan at ~/.claude/plans/joyful-marinating-sutton.md for architecture, critical files, risks, and open questions. This task is phase 6 of 7 in the legal-ai UI rewrite from vanilla HTML to Next.js 15 + shadcn/ui.",
         "testStrategy": "Lighthouse a11y score > 90, all loading states visible, errors show toasts, README has documented smoke test steps.",
-        "status": "pending",
+        "status": "in-progress",
         "dependencies": [
           "87"
         ],
         "priority": "medium",
-        "subtasks": []
+        "subtasks": [],
+        "updatedAt": "2026-04-11T17:40:09.247Z"
       },
       {
         "id": "89",
@@ -899,9 +900,9 @@
     ],
     "metadata": {
       "version": "1.0.0",
-      "lastModified": "2026-04-11T17:28:06.563Z",
+      "lastModified": "2026-04-11T17:40:09.248Z",
       "taskCount": 59,
-      "completedCount": 54,
+      "completedCount": 55,
       "tags": [
         "master"
       ]