Phase 5: secondary screens (diagnostics, skills, training)

Port the remaining read views from the vanilla UI to Next.js:

- /diagnostics — system health snapshot (DB connected, table counts,
  active tasks, failed and stuck documents). Uses the existing
  /api/system/diagnostics payload with a 10s refetchInterval so the
  page self-updates while the user watches.
- /skills — Paperclip skill inventory with sync status (DB-only,
  disk-only, synced, not-synced) as a card grid driven by
  /api/admin/skills.
- /training — Dafna's style portrait as three tabs on one page:
  * Report: corpus KPIs + CSS conic-gradient subject donut
    (SubjectDonut ported from index.html renderHero) + horizontal
    anatomy bars + top-12 signature phrases.
  * Corpus: TanStack Table of style_corpus rows with an inline
    delete mutation (useDeleteCorpusEntry invalidates both the
    corpus list and the style report so KPIs update).
  * Compare: two-decision selector backed by /api/training/compare,
    side-by-side panels plus shared / only-A / only-B pattern
    lists.

New API modules: lib/api/system.ts, lib/api/skills.ts,
lib/api/training.ts. All three use TanStack Query with staleTime
profiles tuned per endpoint (10s for diagnostics, 30s for skills,
60s for training reports).

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

.taskmaster/tasks/tasks.json

@@ -848,12 +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": "pending",
+        "status": "in-progress",
         "dependencies": [
           "86"
         ],
         "priority": "medium",
-        "subtasks": []
+        "subtasks": [],
+        "updatedAt": "2026-04-11T17:28:06.562Z"
       },
       {
         "id": "88",
@@ -887,20 +888,20 @@
         "description": "Add practice_area + appeal_subtype to the wizard, types, schema, case header, and cases table. Gap identified after backend commit 26d09d6 (multi-tenant axis) — new Next.js UI has zero integration while vanilla UI is fully wired. Plan: ~/.claude/plans/woolly-cooking-graham.md",
         "details": "",
         "testStrategy": "",
-        "status": "in-progress",
+        "status": "done",
         "dependencies": [
           "86"
         ],
         "priority": "high",
         "subtasks": [],
-        "updatedAt": "2026-04-11T17:13:13.931Z"
+        "updatedAt": "2026-04-11T17:15:57.831Z"
       }
     ],
     "metadata": {
       "version": "1.0.0",
-      "lastModified": "2026-04-11T17:13:13.932Z",
+      "lastModified": "2026-04-11T17:28:06.563Z",
       "taskCount": 59,
-      "completedCount": 53,
+      "completedCount": 54,
       "tags": [
         "master"
       ]