Migrate from JSON to PostgreSQL, update SLA to 99.5%

- Replace JSON file storage with PostgreSQL (pg package)
- Add db.ts service for connection pool and schema init
- Rewrite keys.ts, verification.ts, usage.ts for async PostgreSQL
- Update all routes for async function signatures
- Add migration script (scripts/migrate-to-postgres.mjs)
- Update docker-compose.yml with DATABASE_* env vars
- Change SLA from 99.9% to 99.5% in landing page

src/index.ts

@@ -11,19 +11,17 @@ import { recoverRouter } from "./routes/recover.js";
 import { billingRouter } from "./routes/billing.js";
 import { emailChangeRouter } from "./routes/email-change.js";
 import { authMiddleware } from "./middleware/auth.js";
-import { usageMiddleware } from "./middleware/usage.js";
+import { usageMiddleware, loadUsageData } from "./middleware/usage.js";
 import { getUsageStats } from "./middleware/usage.js";
 import { pdfRateLimitMiddleware, getConcurrencyStats } from "./middleware/pdfRateLimit.js";
 import { initBrowser, closeBrowser } from "./services/browser.js";
 import { loadKeys, getAllKeys } from "./services/keys.js";
-import { verifyToken } from "./services/verification.js";
+import { verifyToken, loadVerifications } from "./services/verification.js";
+import { initDatabase } from "./services/db.js";
 
 const app = express();
 const PORT = parseInt(process.env.PORT || "3100", 10);
 
-// Load API keys from persistent store
-loadKeys();
-
 app.use(helmet({ crossOriginResourcePolicy: { policy: "cross-origin" } }));
 
 // Differentiated CORS middleware
@@ -34,10 +32,8 @@ app.use((req, res, next) => {
                              req.path.startsWith('/v1/email-change');
   
   if (isAuthBillingRoute) {
-    // Auth/billing routes: restrict to docfast.dev
     res.setHeader("Access-Control-Allow-Origin", "https://docfast.dev");
   } else {
-    // Conversion API routes: allow all origins
     res.setHeader("Access-Control-Allow-Origin", "*");
   }
   
@@ -60,7 +56,7 @@ app.use(express.text({ limit: "2mb", type: "text/*" }));
 // Trust nginx proxy
 app.set("trust proxy", 1);
 
-// Global rate limiting - reduced from 10,000 to reasonable limit
+// Global rate limiting
 const limiter = rateLimit({
   windowMs: 60_000,
   max: 100,
@@ -174,6 +170,14 @@ app.get("/api", (_req, res) => {
 });
 
 async function start() {
+  // Initialize PostgreSQL
+  await initDatabase();
+  
+  // Load data from PostgreSQL
+  await loadKeys();
+  await loadVerifications();
+  await loadUsageData();
+  
   await initBrowser();
   console.log(`Loaded ${getAllKeys().length} API keys`);
   app.listen(PORT, () => console.log(`DocFast API running on :${PORT}`));