fix: price_monitor crash when shares is string + type guard in write_holding_strategy

Root cause: holding_strategies.shares field got set to literal string
'write_holding_strategy' for 6 records, causing TypeError at
price_monitor.py line 611 ('>' not supported between str and int).

Fixes:
1. price_monitor.py: Replace set comprehension with safe loop that
   checks isinstance before comparison. Non-numeric shares treated
   as holdings for safety.
2. mofin_db.py write_holding_strategy: Add type guard that resets
   non-numeric shares to 0 with warning.
3. Data fix: Updated 5 corrupted holding_strategies records from
   holdings table (300035/300308/300750/518880/00700).
   Set 002594 (watchlist) shares=0.

deploy/profile-scripts/price_monitor.py

@@ -608,7 +608,16 @@ def run_once(round_label=""):
     # === 第三步：买入区偏离检测 + 自动重评 ===
     reassesed_codes = []
     # 先做急跌检测（仅持仓，自选股不推送暴跌告警）
-    holdings_codes = {d["code"] for d in active if (d.get("shares") or 0) > 0}
+    holdings_codes = set()
+    for d in active:
+        shares = d.get("shares", 0)
+        if isinstance(shares, (int, float)):
+            if shares > 0:
+                holdings_codes.add(d["code"])
+        else:
+            # 非数值shares（如被错误写入的字符串），兜底处理
+            holdings_codes.add(d["code"])
+            print(f"  [WARN] {d.get('code')} shares为非数值({shares!r})，视为持仓处理", flush=True)
     for d in active:
         code = d["code"]
         # 非持仓跳过