fix(mcp): answer the discovery documents under the server address too

A client handed https://host/mcp as the server address looks for the
well-known documents below that path instead of asking the origin, and every
one of those probes fell through to the web app: 200 with an HTML body, which
reads to the client as "this server has no OAuth" (Open WebUI reports it as an
unexpected mimetype). The three documents are served under /mcp/.well-known
now, anything else there answers a JSON 404, and the RFC 8414 path-inserted
form /.well-known/oauth-authorization-server/mcp serves the metadata instead
of 404. The wiki says which redirect URI belongs to the client and that a
plain-HTTP APP_URL leaves the discovery document pointing at localhost.

server/src/nest/platform/platform.module.ts

@@ -1,6 +1,6 @@
 import { Module, type MiddlewareConsumer, type NestModule } from '@nestjs/common';
 import { AddonsModule } from '../addons/addons.module';
-import { DiscoveryController } from './discovery.controller';
+import { DiscoveryController, McpResourceDiscoveryController } from './discovery.controller';
 import { DiscoveryMetadataService } from './discovery-metadata.service';
 import { mcpMetadataMiddlewareProvider } from './mcp-metadata.middleware';
 import { ConsentCoopMiddleware } from './consent-coop.middleware';
@@ -23,8 +23,8 @@ import { ConsentCoopMiddleware } from './consent-coop.middleware';
  */
 @Module({
   imports: [AddonsModule],
-  controllers: [DiscoveryController],
-  providers: [DiscoveryMetadataService, mcpMetadataMiddlewareProvider, ConsentCoopMiddleware],
+  controllers: [DiscoveryController, McpResourceDiscoveryController],
+  providers: [DiscoveryMetadataService, DiscoveryController, mcpMetadataMiddlewareProvider, ConsentCoopMiddleware],
 })
 export class PlatformModule implements NestModule {
   configure(consumer: MiddlewareConsumer): void {