server+web: shifts — open/close + signed Z-report (manned mode)

A shift is two signed ledger events, no mutable table: new shift_open event
type + existing shift_z_report. The operator is the logged-in user (carried in
event identity); a shift is open iff their latest shift event is a shift_open.

ShiftService: close sums payment events in [start,end] by tender (cash/card, by
payment time), appends the signed shift_z_report (totals/counts/window), and
prints via a new generic PrinterDevice.printReport(title, lines) (Rongta ESC/POS
text) to a booth-receipt printer. Print is best-effort — a failed print does not
undo the signed close.

Routes (cashier/operator/admin): GET /api/shift/current, POST /api/shift/open
(409 if open), POST /api/shift/close (409 if none). Web ShiftControl in the
shell (non-readonly): Start/End + Z-report totals.

Verified: open -> double-open 409 -> payments (cash+card; one outside the window
excluded) -> close totals correct + signed + printed -> close-again 409 ->
re-open ok; readonly 403; verifyChain ok.

apps/web/src/api.ts

@@ -277,3 +277,30 @@ export function revokePermit(id: string): Promise<Permit> {
 export function deletePermit(id: string): Promise<void> {
   return apiFetch(`/api/permits/${id}`, { method: "DELETE" });
 }
+
+// --- Shifts ---------------------------------------------------------------
+
+export interface ShiftStatus {
+  operator: string;
+  open: { startedAt: string } | null;
+}
+export interface ShiftReport {
+  operator: string;
+  startedAt: string;
+  endedAt: string;
+  cashTotalMinor: number;
+  cardTotalMinor: number;
+  currency: string | null;
+  paymentCount: number;
+  printed: boolean;
+}
+
+export function fetchShift(): Promise<ShiftStatus> {
+  return apiFetch("/api/shift/current");
+}
+export function openShift(): Promise<{ startedAt: string }> {
+  return apiFetch("/api/shift/open", { method: "POST" });
+}
+export function closeShift(): Promise<ShiftReport> {
+  return apiFetch("/api/shift/close", { method: "POST" });
+}