Check select-all, filtered total, deposit slip layout fixes

- Add select-all checkbox to checks table header; checks/unchecks all
  visible (filtered) rows; supports indeterminate state
- Add summary bar below checks toolbar showing count and total amount
  of filtered checks
- Deposit slip: output to full 8.5x11 letter page for trimming
- Deposit slip: remove beige left strip fill (white background)
- Deposit slip: remove vertical separator between depositor/bank info
- Deposit slip: stack bank info below account info instead of side-by-side
- Deposit slip: lower date underline position
- Deposit slip left strip: flip text orientation to read tilt-left
  (rotate 90 instead of -90; reposition all strip element anchors)
- Deposit slip left strip: center MICR and labels in strip width
- Deposit slip total: include decimal point in rotated digit amount

public/css/style.css

@@ -79,6 +79,14 @@ header {
 .toolbar-right { display: flex; align-items: center; gap: 8px; }
 .toolbar label { font-size: 12px; font-weight: 500; color: var(--text-muted); }
 
+.checks-summary {
+  padding: 3px 12px;
+  font-size: 12px;
+  color: var(--text-muted);
+  flex-shrink: 0;
+  min-height: 20px;
+}
+
 select {
   border: 1px solid var(--border);
   border-radius: 4px;