Add QuickBooks Online CSV importer for checks and deposits

Two-tab modal: "Checks to Print" parses QBO Transaction List / Check
Detail CSV exports; "Deposits" parses QBO Deposit Detail CSV exports
and groups by date. Both tabs show a preview before confirming import.

src/app.js

@@ -154,6 +154,8 @@ app.post('/api/account/setup', (req, res) => {
 
 // TODO: Add deposit slip support -- deposits table, PDF generation, ledger, and slide-in entry form
 
+app.use('/api/qbo-import', require('./routes/qbo-import'));
+
 // .mdb import endpoint — always creates a new account
 app.post('/api/import', upload.single('mdbfile'), (req, res) => {
   if (!req.file) return res.status(400).json({ error: 'No file uploaded.' });