feat(polymarket): outcome-aware scoring and synthesis instructions

- _compute_text_similarity() now checks outcome names with bidirectional
  substring matching (0.85) and token overlap (0.7), not just event titles
- Collect outcomes from ALL active markets per event, filter to >1% price
- Reorder outcome_prices to surface topic-matching outcome before top-3 truncation
- Add SKILL.md "Prediction Markets" synthesis section with structural/long-term
  market preference, domain examples, citation format, and narrative weaving
- Add Polymarket to citation priority list between HN and Web
- Update stats box template to show up to 5 market odds
- Fix render.py "vol24h" label to "volume"
- Add NCAA seed fixture event for outcome-only matching tests
- 82 polymarket tests pass (14 new)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

fixtures/polymarket_sample.json

@@ -182,6 +182,37 @@
         }
       ]
     },
+    {
+      "id": "evt-ncaa-seed",
+      "title": "Who will be the #1 overall seed in the 2026 NCAA Tournament?",
+      "slug": "ncaa-1-seed-2026",
+      "active": true,
+      "closed": false,
+      "updatedAt": "2026-02-25T14:00:00.000Z",
+      "volume24hr": 200000,
+      "volume1wk": 900000,
+      "volume1mo": 2500000,
+      "volume": 6000000,
+      "liquidity": 1500000,
+      "competitive": 0.88,
+      "commentCount": 12,
+      "markets": [
+        {
+          "id": "mkt-ncaa-seed-1",
+          "question": "Who will be the #1 overall seed in the 2026 NCAA Tournament?",
+          "active": true,
+          "closed": false,
+          "outcomes": "[\"Duke\", \"Arizona\", \"Houston\", \"Auburn\", \"Michigan\"]",
+          "outcomePrices": "[\"0.30\", \"0.28\", \"0.20\", \"0.12\", \"0.10\"]",
+          "volume": "2500000",
+          "volume24hr": "200000",
+          "liquidity": "1500000",
+          "oneDayPriceChange": 0.02,
+          "oneWeekPriceChange": 0.06,
+          "oneMonthPriceChange": 0.10
+        }
+      ]
+    },
     {
       "id": "evt-tangential",
       "title": "Will AI regulation pass in 2026?",