后端深度清理 Polymarket：删除 readonly 层+WS 缓存+market_scan API

删除 src/data_collection/polymarket_readonly.py(2500行)和 polymarket_ws_cache.py。city_payloads 移除 _get_polymarket_layer/_top_probability_bucket/build_city_market_scan_payload。city.py 移除 /market-scan 和 /holders 路由。scan_terminal 移除 skip_polymarket。

web/scan_terminal_city_row.py

@@ -5,7 +5,7 @@ from datetime import datetime, timedelta
 from typing import Any, Dict, List, Optional
 
 from web.core import CITIES
-from web.analysis_service import _analyze, _build_city_market_scan_payload
+from web.analysis_service import _analyze
 from web.scan_city_ai_helpers import _safe_float
 from web.scan_terminal_ai_compact import _build_metar_decision_context
 from web.scan_terminal_filters import (
@@ -164,14 +164,7 @@ def _scan_city_terminal_rows(
     candidate_total = 0
 
     for target_date in target_dates:
-        payload = _build_city_market_scan_payload(
-            data,
-            market_slug=None,
-            target_date=target_date,
-            lite=True,
-            scan_filters=filters,
-        )
-        scan = payload.get("market_scan") or {}
+        scan = {"available": False}
         candidate_total += int(scan.get("candidate_count") or 0)
         raw_rows = scan.get("scan_rows")
         if not isinstance(raw_rows, list) or not raw_rows: