fix: cancelled tier, remove key logging, add billing rate limits

- Add 'cancelled' tier (0 req/month) for downgraded subscriptions
- Remove full API key from recovery endpoint logs (security)
- Add IP-based rate limiting (10/15min) to billing endpoints
- Bump version to 0.7.0
- 4 new tests (338 total)

src/services/__tests__/keys.test.ts

@@ -1,5 +1,5 @@
 import { describe, it, expect, vi, beforeEach } from 'vitest'
-import { getTierLimit, getKeyByEmail, getCustomerIdByEmail } from '../keys.js'
+import { getTierLimit, getKeyByEmail, getCustomerIdByEmail, downgradeByCustomer } from '../keys.js'
 
 // Mock the db module
 vi.mock('../db.js', () => ({
@@ -25,6 +25,10 @@ describe('getTierLimit', () => {
     expect(getTierLimit('business')).toBe(25000)
   })
 
+  it('should return 0 for cancelled tier', () => {
+    expect(getTierLimit('cancelled')).toBe(0)
+  })
+
   it('should return 100 for unknown tier', () => {
     expect(getTierLimit('enterprise')).toBe(100)
   })
@@ -124,3 +128,20 @@ describe('getCustomerIdByEmail', () => {
     expect(result).toBeUndefined()
   })
 })
+
+describe('downgradeByCustomer', () => {
+  beforeEach(() => {
+    vi.clearAllMocks()
+  })
+
+  it('should set tier to cancelled instead of free', async () => {
+    vi.mocked(queryWithRetry).mockResolvedValue({ rows: [] })
+
+    await downgradeByCustomer('cus_test_123')
+
+    expect(queryWithRetry).toHaveBeenCalledWith(
+      expect.stringContaining("'cancelled'"),
+      ['cus_test_123']
+    )
+  })
+})

src/services/keys.ts

@@ -4,7 +4,7 @@ import { queryWithRetry } from "./db.js";
 
 export interface ApiKey {
   key: string;
-  tier: "free" | "starter" | "pro" | "business";
+  tier: "free" | "cancelled" | "starter" | "pro" | "business";
   email: string;
   createdAt: string;
   stripeCustomerId?: string;
@@ -130,6 +130,7 @@ export function getAllKeys(): ApiKey[] {
 export function getTierLimit(tier: string): number {
   switch (tier) {
     case "free": return 100;
+    case "cancelled": return 0;
     case "starter": return 1000;
     case "pro": return 5000;
     case "business": return 25000;
@@ -184,16 +185,16 @@ export async function createPaidKey(email: string, tier: "starter" | "pro" | "bu
 
 export async function downgradeByCustomer(customerId: string): Promise<void> {
   await queryWithRetry(
-    "UPDATE api_keys SET tier = 'free', stripe_customer_id = NULL WHERE stripe_customer_id = $1",
+    "UPDATE api_keys SET tier = 'cancelled', stripe_customer_id = NULL WHERE stripe_customer_id = $1",
     [customerId]
   );
   for (const k of keysCache) {
     if (k.stripeCustomerId === customerId) {
-      k.tier = "free";
+      k.tier = "cancelled";
       k.stripeCustomerId = undefined;
     }
   }
-  logger.info({ customerId }, "Downgraded customer to free");
+  logger.info({ customerId }, "Downgraded customer to cancelled");
 }
 
 export async function updateEmailByCustomer(customerId: string, newEmail: string): Promise<void> {