feat: wire up swagger-jsdoc dynamic spec, delete static openapi.json

- Create src/swagger.ts config module for swagger-jsdoc
- Add GET /openapi.json dynamic route (generated from @openapi annotations)
- Delete static public/openapi.json (was drifting from code)
- Add @openapi annotation for deprecated /v1/signup/free in index.ts
- Import swaggerSpec into index.ts
- All 12 endpoints now code-driven: demo/html, demo/markdown, convert/html,
  convert/markdown, convert/url, templates, templates/{id}/render,
  recover, recover/verify, billing/checkout, signup/free, health

src/index.ts

@@ -24,6 +24,7 @@ import { initBrowser, closeBrowser } from "./services/browser.js";
 import { loadKeys, getAllKeys } from "./services/keys.js";
 import { verifyToken, loadVerifications } from "./services/verification.js";
 import { initDatabase, pool } from "./services/db.js";
+import { swaggerSpec } from "./swagger.js";
 
 const app = express();
 const PORT = parseInt(process.env.PORT || "3100", 10);
@@ -98,6 +99,28 @@ app.use(limiter);
 // Public routes
 app.use("/health", healthRouter);
 app.use("/v1/demo", express.json({ limit: "50kb" }), pdfRateLimitMiddleware, demoRouter);
+/**
+ * @openapi
+ * /v1/signup/free:
+ *   post:
+ *     tags: [Account]
+ *     summary: Request a free API key (discontinued)
+ *     description: Free accounts have been discontinued. Use the demo endpoints or upgrade to Pro.
+ *     responses:
+ *       410:
+ *         description: Feature discontinued
+ *         content:
+ *           application/json:
+ *             schema:
+ *               type: object
+ *               properties:
+ *                 error:
+ *                   type: string
+ *                 demo_endpoint:
+ *                   type: string
+ *                 pro_url:
+ *                   type: string
+ */
 app.use("/v1/signup", (_req, res) => {
   res.status(410).json({
     error: "Free accounts have been discontinued. Try our demo at POST /v1/demo/html or upgrade to Pro at https://docfast.dev",
@@ -196,6 +219,11 @@ app.get("/favicon.ico", (_req, res) => {
   res.sendFile(path.join(__dirname, "../public/favicon.svg"));
 });
 
+// Dynamic OpenAPI spec — generated from @openapi JSDoc annotations at startup
+app.get("/openapi.json", (_req, res) => {
+  res.json(swaggerSpec);
+});
+
 // Docs page (clean URL)
 app.get("/docs", (_req, res) => {
   // Swagger UI 5.x uses new Function() (via ajv) for JSON schema validation.