Add auto-trade scheduler with batch locking, commission gross-up, and sync gate

- Auto-trade scheduler fires every 60s; uses Promise.allSettled batch so no new trades fire while any position from the current batch is open
- Commission gross-up: read entryCommission from cash.realizedPnL after fill (fallback 2.5×contracts), grossTarget = target + 2×entryCommission
- Sync gate: TradovateClient.syncComplete flag; scheduler skips tick until every client finishes initial position/balance sync
- Contracts formula changed to Math.ceil so $1500 target = 2 contracts
- Removed all fee caching (perContractFees, recentFills, fillFee handler) from tradovate-class.ts
- Removed firm_fees table, getFirmFees, upsertFirmFee from db.ts
- Deleted instrument-configs API routes; removed Fees UI from firm settings page
- /api/instruments returns full {symbol, enabled}[] objects; dashboard filters to enabled-only for trade selector
- Added auto-trade, debug, orders, settings, and trade API routes
- Instrument selector on dashboard now driven by enabled instruments from DB

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

app/api/settings/route.ts

@@ -0,0 +1,31 @@
+import { NextRequest, NextResponse } from 'next/server';
+import { getSetting, setSetting } from '@/lib/db';
+
+const VALID_KEYS = ['max_concurrent_accounts'] as const;
+type SettingKey = typeof VALID_KEYS[number];
+
+export async function GET() {
+    const result: Record<string, string | null> = {};
+    for (const key of VALID_KEYS) {
+        result[key] = getSetting(key);
+    }
+    return NextResponse.json(result);
+}
+
+export async function PATCH(req: NextRequest) {
+    try {
+        const body = await req.json() as Partial<Record<SettingKey, string | number>>;
+
+        for (const key of VALID_KEYS) {
+            if (key in body) {
+                const raw = body[key];
+                if (raw === undefined || raw === null) continue;
+                setSetting(key, String(raw));
+            }
+        }
+
+        return NextResponse.json({ ok: true });
+    } catch (err: any) {
+        return NextResponse.json({ error: err?.message ?? 'Failed to save settings' }, { status: 500 });
+    }
+}