feat(stock): holdings_signals 테이블 + CRUD

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

stock/app/test_holdings_db.py

@@ -0,0 +1,24 @@
+import os, tempfile, importlib
+
+def _fresh_db(monkeypatch):
+    tmp = tempfile.mkdtemp()
+    from app import db
+    monkeypatch.setattr(db, "DB_PATH", os.path.join(tmp, "stock.db"))
+    db.init_db()
+    return db
+
+def test_holdings_signals_table_and_upsert(monkeypatch):
+    db = _fresh_db(monkeypatch)
+    db.upsert_holdings_signal(date="2026-05-29", ticker="005930", name="삼성전자",
+        action="hold", tech_score=72.0, exit_flags={"stop_loss": False},
+        issues=[{"type": "news", "severity": "low", "summary": "x"}],
+        close=80000, pnl_rate=5.2, reasons="강건")
+    db.upsert_holdings_signal(date="2026-05-29", ticker="005930", name="삼성전자",
+        action="trim", tech_score=60.0, exit_flags={"ma50_break": True},
+        issues=[], close=79000, pnl_rate=3.0, reasons="MA50 이탈")
+    rows = db.get_holdings_signals(date="2026-05-29")
+    assert len(rows) == 1                       # upsert 멱등
+    assert rows[0]["action"] == "trim"
+    assert rows[0]["exit_flags"]["ma50_break"] is True   # JSON 역직렬화
+    hist = db.get_holdings_signal_history("005930", days=30)
+    assert len(hist) == 1