Persist daily P&L beyond 28-day Tradovate window

Adds a daily_pnl SQLite table that accumulates trade history indefinitely.
On each hourly fetch, fresh API data is upserted (not replaced) so entries
older than Tradovate's 28-day limit are preserved. Cache is loaded at startup
and used as fallback when both report requests fail.

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

lib/db.ts

@@ -201,6 +201,32 @@ export function setInstrumentEnabled(symbol: string, enabled: boolean): boolean
     return result.changes > 0;
 }
 
+// ── Daily P&L Cache ──────────────────────────────────────────────────────────
+
+db.exec(`
+    CREATE TABLE IF NOT EXISTS daily_pnl (
+        account_id   INTEGER NOT NULL,
+        account_name TEXT    NOT NULL,
+        date         TEXT    NOT NULL,
+        pnl          REAL    NOT NULL,
+        PRIMARY KEY (account_id, date)
+    );
+`);
+
+export function saveDailyPnL(accountId: number, accountName: string, entries: { date: string; pnl: number }[]): void {
+    const ins = db.prepare('INSERT OR REPLACE INTO daily_pnl (account_id, account_name, date, pnl) VALUES (?, ?, ?, ?)');
+    const txn = db.transaction(() => {
+        for (const e of entries) {
+            ins.run(accountId, accountName, e.date, e.pnl);
+        }
+    });
+    txn();
+}
+
+export function loadDailyPnL(accountId: number): { date: string; pnl: number }[] {
+    return (db.prepare('SELECT date, pnl FROM daily_pnl WHERE account_id = ? ORDER BY date').all(accountId) as { date: string; pnl: number }[]);
+}
+
 // ── Firm banned symbols ───────────────────────────────────────────────────────
 
 db.exec(`