Align admin optional-services billing UI with runtimes and bill RAM proportionally.

Split optional pricing vs deploy defaults and move custom domain to its own card; parse Mi as decimal GB so fractional memory scales linearly with per-GB rates. Deploy wizard hides env and optional services for WordPress and sanitizes create payloads.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/src/billing/pricing-catalog.service.spec.ts

@@ -76,6 +76,29 @@ describe('PricingCatalogService', () => {
     expect(service.parseCpuToCores('2')).toBe(2);
   });
 
+  it('parses memory Mi to decimal GB for proportional billing (500Mi = 0.5 GB)', () => {
+    expect(service.parseMemoryToGb('500Mi')).toBe(0.5);
+    expect(service.parseMemoryToGb('1000Mi')).toBe(1);
+    expect(service.parseMemoryToGb('1Gi')).toBe(1);
+  });
+
+  it('bills memory proportional to decimal GB (500Mi at half the per-GB monthly rate)', () => {
+    const rates = [
+      {
+        runtime: AppRuntime.NODEJS,
+        resourceType: PricingResourceType.MEMORY_PER_GB,
+        hourlyPrice: 0,
+        monthlyPrice: 10_000,
+        yearlyPrice: 0,
+        isActive: true,
+      },
+    ] as PricingRate[];
+
+    const dto = { ...baseDto(), memoryLimit: '500Mi' };
+    const result = service.computeTotalsWithRates(dto, rates, emptyOptional());
+    expect(result.monthly).toBe(5000);
+  });
+
   it('computes CPU line with cycle-native prices (no conversion)', () => {
     const rates = [
       {