Add Hungarian Forint (HUF) currency for filament cost tracking

Closes #579 — adds HUF with symbol "Ft" to the supported currencies
  list so Hungarian users can track filament costs in their local currency.

frontend/src/__tests__/utils/currency.test.ts

@@ -37,7 +37,7 @@ describe('SUPPORTED_CURRENCIES', () => {
     expect(SUPPORTED_CURRENCIES.find((c) => c.code === 'INR')).toBeDefined();
   });
 
-  it('has 25 entries', () => {
-    expect(SUPPORTED_CURRENCIES).toHaveLength(25);
+  it('has 26 entries', () => {
+    expect(SUPPORTED_CURRENCIES).toHaveLength(26);
   });
 });