chore: remove response fileting as this should be delegated to fastify schema validators

1. Fastify's schema validation and serialization already do strong schem validation.
1. Appllying blanket filters will make code brittle (might miss variations), can have performance
 impacts, and can cause unexpected data loss making ti hard to debug on where the data sent
 was filtered.

Author: abose

src/server.js

@@ -54,25 +54,6 @@ server.register(rateLimit, {
     }
 });
 
-// Response Sanitization
-function sanitizeResponse(data) {
-    const sensitiveFields = ['password', 'token', 'secret', 'key', 'auth'];
-    if (typeof data === 'object' && data !== null) {
-        const sanitized = {...data};
-        Object.keys(sanitized).forEach(key => {
-            if (sensitiveFields.includes(key.toLowerCase())) {
-                delete sanitized[key];
-            }
-        });
-        return sanitized;
-    }
-    return data;
-}
-
-server.addHook('preSerialization', (request, reply, payload, done) => {
-    done(null, sanitizeResponse(payload));
-});
-
 // Global error handler with correlation ID
 server.setErrorHandler((error, request, reply) => {
     const errorLog = {