Coach view (stub)

How to use

1. Open index.html and complete a diagnostic (placeholder items).
2. On the results screen, toggle Coach for tag heatmap, miss log, domain vs weights, and CSV export.
3. Download weakness-map JSON for offline tracking / future API.

Same attempt powers both learner and coach views. Learner copy stays encouraging; coach gets trap types, unanswered count, and hot-spot flags from the blueprint.

Expected weakness-map fields

{
  "attemptId": "...",
  "takenAt": "ISO-8601",
  "overallPct": 0.62,
  "secondsUsed": 4100,
  "domains": [
    {"id": "D1", "correct": 8, "total": 14},
    {"id": "D2", "correct": 11, "total": 18},
    {"id": "D3", "correct": 6, "total": 8}
  ],
  "tags": [
    {"id": "D1.scorp-basis-aaa", "correct": 1, "total": 3, "rank": 1}
  ],
  "path": ["D1.scorp-basis-aaa", "D1.partnership-basis", "D2.depr-179-bonus"]
}