fix(ingestor): align WebSocket subscribe + routing with live API (#105)

* fix(ingestor): align WebSocket subscribe + routing with live API

The Polymarket ws-live-data WebSocket requires `action: "subscribe"` in
the subscribe envelope. Without it the server accepts the connection but
never delivers trade events, causing the tracker to silently produce
zero alerts.

Additionally, incoming frames are shaped `{connection_id, payload:{...}}`
-- they do NOT echo the `topic`/`type` keys we sent. The previous routing
check matched nothing and every real trade was silently dropped.

Changes:
- Add `action: "subscribe"` to subscription message
- Route incoming messages by payload shape (transactionHash + proxyWallet)
- Add ratchet tests for payload routing edge cases
- Rewrite README as agent-first with <2min quickstart
- Add skill draft (docs/skill-tracking-prediction-market-flow.md)

Closes #89

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

* fix(lint): remove unused imports in test_pipeline_persistence

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

* style: apply ruff formatting

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

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

src/polymarket_insider_tracker/ingestor/websocket.py

@@ -150,7 +150,7 @@ class TradeStreamHandler:
         elif self._market_filter:
             subscription["filters"] = json.dumps({"market_slug": self._market_filter})
 
-        return {"subscriptions": [subscription]}
+        return {"action": "subscribe", "subscriptions": [subscription]}
 
     async def _connect(self) -> ClientConnection:
         """Establish WebSocket connection."""
@@ -183,12 +183,13 @@ class TradeStreamHandler:
         try:
             data = json.loads(message)
 
-            # Check if this is a trade message
-            topic = data.get("topic")
-            msg_type = data.get("type")
-
-            if topic == "activity" and msg_type == "trades":
-                payload = data.get("payload", {})
+            # ws-live-data pushes {connection_id, payload:{...trade fields}}
+            payload = data.get("payload")
+            if (
+                isinstance(payload, dict)
+                and "transactionHash" in payload
+                and "proxyWallet" in payload
+            ):
                 trade = TradeEvent.from_websocket_message(payload)
 
                 self._stats.trades_received += 1
@@ -208,8 +209,7 @@ class TradeStreamHandler:
                     logger.error("Error in trade callback: %s", e)
 
             else:
-                # Log other message types for debugging
-                logger.debug("Received message: topic=%s type=%s", topic, msg_type)
+                logger.debug("Received non-trade message: %s", str(data)[:120])
 
         except json.JSONDecodeError as e:
             logger.warning("Invalid JSON message: %s", e)