feat(api): implement /api/user/[user] endpoint

src/app/api/user/[user]/swagger.ts

@@ -0,0 +1,33 @@
+import { PublicUserResponseSchema } from '../validation';
+import {
+  notAuthenticatedResponse,
+  userNotFoundResponse,
+} from '@/lib/defaultApiResponses';
+import { OpenAPIRegistry } from '@asteasolutions/zod-to-openapi';
+import zod from 'zod/v4';
+import { UserIdParamSchema } from '../../validation';
+
+export default function registerSwaggerPaths(registry: OpenAPIRegistry) {
+  registry.registerPath({
+    method: 'get',
+    path: '/api/user/{user}',
+    request: {
+      params: zod.object({
+        user: UserIdParamSchema,
+      }),
+    },
+    responses: {
+      200: {
+        description: 'User information retrieved successfully.',
+        content: {
+          'application/json': {
+            schema: PublicUserResponseSchema,
+          },
+        },
+      },
+      ...notAuthenticatedResponse,
+      ...userNotFoundResponse,
+    },
+    tags: ['User'],
+  });
+}