fix(machine): production hardware fixes for Douro cash-out

- Fix cassette denominations: Douro uses Q100/Q200, not Q20
- Add hal:get-inventory IPC so renderer can read HAL cassette inventory
- Add balance fetch/display to HAL+IPC init path and idle screen
- Enable/disable bill validator via watch on nested state transitions
- Pass fiatCode to state machine context (was hardcoded to USD)
- Preserve currency across state machine resetContext
- Add CANCEL handler to dispenseError state (was stuck)
- Fix remaining hardcoded $ symbols in CashInView

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

packages/state-machine/src/machine.ts

@@ -17,7 +17,10 @@ import {
 /**
  * Create the ATM state machine with injected services
  */
-export function createATMMachine(services: Partial<ATMServices> = {}) {
+export function createATMMachine(
+  services: Partial<ATMServices> = {},
+  options?: { currency?: string }
+) {
   return setup({
     types: {
       context: {} as ATMContext,
@@ -153,6 +156,7 @@ export function createATMMachine(services: Partial<ATMServices> = {}) {
     actions: {
       resetContext: assign(({ context }) => ({
         ...initialContext,
+        currency: context.currency,
         inventory: context.inventory,
         cashInSessionId: null,
       })),
@@ -372,7 +376,7 @@ export function createATMMachine(services: Partial<ATMServices> = {}) {
   }).createMachine({
     id: 'atm',
     initial: 'idle',
-    context: initialContext,
+    context: { ...initialContext, ...(options?.currency ? { currency: options.currency } : {}) },
     states: {
       idle: {
         entry: 'resetContext',
@@ -637,6 +641,7 @@ export function createATMMachine(services: Partial<ATMServices> = {}) {
                 target: 'dispensingCash',
                 actions: 'incrementRetry',
               },
+              CANCEL: '#atm.idle',
             },
           },
           error: {