feat(01-02): add /ready endpoint with database connectivity check

- Add GET /ready endpoint that checks database connection
- Returns 200 'ready' when connected, 503 when not
- Update Routes to require DataSource dependency
- Provide dataSourceLayer in Main.scala
- Use 'hikari' prefix for HikariCP config to avoid ZIO config conflict

summercms/src/api/Routes.scala

@@ -1,6 +1,7 @@
 package api
 
 import zio.http.*
+import javax.sql.DataSource
 
 /** Route composition point
   *
@@ -8,7 +9,7 @@ import zio.http.*
   */
 object Routes {
 
-  val routes: Routes[Any, Response] =
+  val routes: Routes[DataSource, Response] =
     HealthRoutes.routes
 
 }