Add Steam API client, service, controller

Introduce Steam integration: add SteamClientConfig (RestClient bean), SteamApiService (calls GetPlayerSummaries and returns a Player DTO), SteamPlayerSummaryResponse DTO, and SteamTestController (/api/steam/test/{steamId}) for quick testing. Update SecurityConfig to permit the test endpoint and adjust the SecurityFilterChain bean signature. Add Steam API settings: base-url in application.yml and a dev API key in application-dev.yml. Includes basic error logging and optional response handling when no player is found.

src/main/resources/application-dev.yml

@@ -7,7 +7,8 @@ app:
   cors:
     # Local development: allow all origins to prevent CORS issues
     allowed-origins: "*"
-
+  steam:
+    api-key: "54EF220BF9A9BF849DB4E33FC4B0FDA3"
 # Optional: Make SQL logs visible for debugging
 spring:
   jpa:
@@ -15,6 +16,4 @@ spring:
 
 security:
   jwt:
-    secret: "NzC9tQP1eTp496SxoVYslH1bqn81Tbfz74NjkFqdcVe7wayjcRN8IeZvJWd1s6NEWgwEXe9rdccvOn2HtJ4fdq"
-  steam:
-    api-key: "54EF220BF9A9BF849DB4E33FC4B0FDA3"
+    secret: "NzC9tQP1eTp496SxoVYslH1bqn81Tbfz74NjkFqdcVe7wayjcRN8IeZvJWd1s6NEWgwEXe9rdccvOn2HtJ4fdq"