chore(self-hosting): add health check endpoint

Add a simple API health route for deployment platforms and container probes, with focused route coverage.

Author: test

apps/sim/app/api/health/route.test.ts

@@ -0,0 +1,17 @@
+/**
+ * @vitest-environment node
+ */
+import { describe, expect, it } from 'vitest'
+import { GET } from '@/app/api/health/route'
+
+describe('GET /api/health', () => {
+  it('returns an ok status payload', async () => {
+    const response = await GET()
+
+    expect(response.status).toBe(200)
+    await expect(response.json()).resolves.toEqual({
+      status: 'ok',
+      timestamp: expect.any(String),
+    })
+  })
+})

apps/sim/app/api/health/route.ts

@@ -0,0 +1,12 @@
+/**
+ * Health check endpoint for deployment platforms and container probes.
+ */
+export async function GET(): Promise<Response> {
+  return Response.json(
+    {
+      status: 'ok',
+      timestamp: new Date().toISOString(),
+    },
+    { status: 200 }
+  )
+}