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/resources/application.conf

@@ -5,7 +5,7 @@ server {
   port = ${?SERVER_PORT}
 }
 
-# Database configuration for ZIO config (used by AppConfig)
+# Database configuration for ZIO config (used by AppConfig.DatabaseConfig)
 database {
   host = "localhost"
   host = ${?DB_HOST}
@@ -20,8 +20,8 @@ database {
 }
 
 # HikariCP configuration for Quill DataSource
-# Reads from "database" prefix via Quill.DataSource.fromPrefix
-database {
+# Uses separate prefix to avoid conflict with ZIO config "database" property
+hikari {
   dataSourceClassName = "org.postgresql.ds.PGSimpleDataSource"
   dataSource {
     serverName = "localhost"