feat: add tenant resolve and health endpoints

Tiku.Api/Controllers/HealthController.cs

@@ -0,0 +1,24 @@
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+using Tiku.Api.Contracts;
+
+namespace Tiku.Api.Controllers;
+
+[ApiController]
+[AllowAnonymous]
+[Produces("application/json")]
+[Route("api/health")]
+public sealed class HealthController : ControllerBase
+{
+    [HttpGet]
+    [EndpointSummary("健康检查")]
+    [EndpointDescription("用于本地、CI 和部署环境 smoke test 的轻量健康检查。")]
+    [ProducesResponseType<HealthResponseDto>(StatusCodes.Status200OK)]
+    public ActionResult<HealthResponseDto> Get()
+    {
+        return Ok(new HealthResponseDto(
+            "ok",
+            "tiku-api",
+            DateTimeOffset.UtcNow));
+    }
+}