refactor(config): cadence-keyed plan id, add getTierAmount, drop per-tier helcimPlanId

tests/server/config/contributions.test.js

@@ -0,0 +1,20 @@
+import { describe, it, expect } from 'vitest'
+import { getTierAmount } from '../../../server/config/contributions.js'
+
+describe('getTierAmount', () => {
+  it('returns monthly amount as-is', () => {
+    expect(getTierAmount({ amount: 5 }, 'monthly')).toBe(5)
+  })
+
+  it('returns annual amount as base * 10', () => {
+    expect(getTierAmount({ amount: 5 }, 'annual')).toBe(50)
+  })
+
+  it('returns annual amount for $50 tier', () => {
+    expect(getTierAmount({ amount: 50 }, 'annual')).toBe(500)
+  })
+
+  it('defaults cadence to monthly', () => {
+    expect(getTierAmount({ amount: 15 })).toBe(15)
+  })
+})