feat: load explicit configuration references and remove implicit env overlays

examples/userService/etc/config.yaml

@@ -1,6 +1,7 @@
-# Non-secret settings only. Environment variables override these values.
+# Defaults are overridden only by fields in this file.
 server:
-  address: '127.0.0.1:8080'
+  transport: "${GO_OMNI_TRANSPORT:-nethttp}"
+  address: "${GO_OMNI_HTTP_ADDR:-127.0.0.1:8080}"
   enableLogger: true
   slowRequestThreshold: 500ms
   shutdownTimeout: 10s
@@ -17,16 +18,19 @@ server:
       compress: true
     redactKeys: []
 storage:
+  filesToken: "${GO_OMNI_FILES_TOKEN:-}"
+  signingKey: "${GO_OMNI_STORAGE_SIGNING_KEY}"
   provider: local
   maxBytes: 33554432
   contentTypes: ['text/plain', 'image/png', 'image/jpeg', 'application/pdf']
   linkTtl: 5m
   requestTimeout: 30s
   root: './var/files'
-  publicUrl: 'http://127.0.0.1:8080/storage/object'
+  publicUrl: "${GO_OMNI_STORAGE_PUBLIC_URL:-http://127.0.0.1:8080/storage/object}"
 
 
 database:
+  dsn: "${GO_OMNI_DB_DSN}"
   driver: mysql
   maxOpenConns: 10
   maxIdleConns: 5