♻️(yprovider) support multiple API keys to separate responsibilities

Support for two API keys has been added to the YProvider microservice to
decouple responsibilities between the collaboration server and other
endpoints. This improves security by scoping keys to specific purposes and
ensures a clearer separation of concerns for easier management and debugging.

src/frontend/servers/y-provider/__tests__/server.test.ts

@@ -14,6 +14,7 @@ jest.mock('../src/env', () => {
     PORT: port,
     COLLABORATION_SERVER_ORIGIN: origin,
     COLLABORATION_SERVER_SECRET: 'test-secret-api-key',
+    Y_PROVIDER_API_KEY: 'yprovider-api-key',
   };
 });
 
@@ -115,7 +116,7 @@ describe('Server Tests', () => {
     const response = await request(app as any)
       .post('/api/convert-markdown')
       .set('Origin', origin)
-      .set('Authorization', 'test-secret-api-key');
+      .set('Authorization', 'yprovider-api-key');
 
     expect(response.status).toBe(400);
     expect(response.body.error).toBe('Invalid request: missing content');
@@ -125,7 +126,7 @@ describe('Server Tests', () => {
     const response = await request(app as any)
       .post('/api/convert-markdown')
       .set('Origin', origin)
-      .set('Authorization', 'test-secret-api-key')
+      .set('Authorization', 'yprovider-api-key')
       .send({
         content: '',
       });