Fix: nginx duplicate MIME type, update version to 0.2.1, improve log rotation

- Remove duplicate text/html from nginx gzip_types (fixes nginx -t warning)
- Update hardcoded API version from 0.2.0 to 0.2.1 to match package.json
- Update logrotate config: daily rotation, 7 days retention, improved postrotate
- Add Docker logging configuration with size/file limits

src/index.ts

@@ -183,7 +183,7 @@ app.get("/docs", (_req, res) => {
 app.get("/api", (_req, res) => {
   res.json({
     name: "DocFast API",
-    version: "0.2.0",
+    version: "0.2.1",
     endpoints: [
       "POST /v1/signup/free — Get a free API key",
       "POST /v1/convert/html",