feat: DB-first architecture with lock-safe writes

- price_monitor: writes live prices to both JSON and mofin.db (holdings + live_prices + portfolio_summary)
- mofin_db: added execute_with_retry/commit_with_retry with exponential backoff on 'database is locked'
- mofin_db: increased timeout 5s->15s, added PRAGMA busy_timeout=15000
- price_monitor retry loop: fixed break-before-if-ok bug (was not retrying on write failure)
- DB connection: WAL mode + retry decorator for all write operations
- cash sync: preserves DB authoritative cash (JSON cash not pushed to DB)

This is the DB-first version. JSON writes remain for dashboard compatibility.
Next step: remove JSON writes entirely for full DB-only architecture.

data/stocks/01211.json

@@ -616,6 +616,21 @@
       "content": "- **比亚迪(01211)** — 现价72.65，止损63.99（距12%）。港股汽车板块整体承压，持续下跌趋势未改。建议：重新审视持股逻辑——如果中线看多理由充分，可考虑将止损下移至60附近；如",
       "report_id": "cron_e02b8bde74f8_2026-06-28_22-11-21"
     },
+    {
+      "time": "2026-07-06T08:55:01.761812",
+      "content": "3. **0714止盈策略严重过期** — 当前 19 个持仓中有约 13 个（68%）的成本价高于止盈价，说明策略数据已随股价下跌严重偏离，大量止损/止盈位明显陈旧（如万科 02202 成本 ¥4.",
+      "report_id": "cron_e02b8bde74f8_2026-07-05_22-05-42"
+    },
+    {
+      "time": "2026-07-06T08:55:01.761812",
+      "content": "3. **策略数据翻新** — 针对成本远高于止盈的 13 个持仓（如 万科02202、比亚迪01211、华恒生物688639、中科电气300035、黄金ETF518880 等），建议逐个审核是否需要",
+      "report_id": "cron_e02b8bde74f8_2026-07-05_22-05-42"
+    },
+    {
+      "time": "2026-07-06T08:55:01.761812",
+      "content": "| **比亚迪(01211)止损临近** | 此前 advice 反复提示止损 ¥81.72、现价距仅 3%。港股比亚迪已是 4.62% 仓位且浮亏 -20.1%，若下周港股继续弱势，止损单需提前挂好",
+      "report_id": "cron_e02b8bde74f8_2026-07-05_22-05-42"
+    },
     {
       "time": "2026-06-01T10:25:54.503460",
       "content": "比亚迪股份(01211) 仓位4.56% +2.27%→ 持有，连涨",