fix(realtime): explicit unsubscribeMarket on subscription cleanup (H0)

[cyl19970726]

Summary

Polymarket WS market channel is stateful: subscribe adds, unsubscribe removes. RealtimeServiceV2.unsubscribe callback only removed local listeners + cleared accumulatedMarketTokenIds, but never sent `{operation:'unsubscribe'}` to the server.

Result: server-side subscription set kept growing across worker lifetime → capacity exhausted → silent drop. Reproduced as 38.5% crypto / 81% cs2 / 1.4% weather miss rate over 24h.

Fix

Send `unsubscribeMarket(tokenIds)` on the active client whenever a subscription is torn down. Try/catch wrapped to prevent recorder hot-path exceptions.

```typescript
if (this.client && this.connected && tokenIds.length > 0) {
try {
this.client.unsubscribeMarket(tokenIds);
} catch (err) {
this.log(`unsubscribeMarket failed (non-fatal): ${err}`);
}
}
```

Test plan

• 6 new unit tests covering happy path, accumulated set cleanup, disconnected/null client guards, throw safety, isolation between subs
• All 85 poly-sdk tests pass
• Verified live on GCE strategy-cs2 (2026-05-03 09:41 UTC):
  • Diag-Raw unique_tokens collapsed from cumulative 1670 → live 8 (= 4 active markets × 2 tokens, no accumulation)
  • 1h crypto miss rate 59.3% → 5-15% (irreducible from market lifecycle)
  • MaxListeners warnings only at startup burst, zero new post-deploy
• 23h+ zero regressions across crypto/cs2/weather domains

Paired PR

• earning-engine: ml-5m-exploration → general-data-infra (submodule bump + Phase A scoring)

🤖 Generated with Claude Code

[cyl19970726]

Superseded — direct push to copy-trading (7c8c7b4) per fork owner's preference. Same H0 fix, no PR flow needed.