feat: implement game listing API and integrate into frontend for display and selection.

protobuf/items.proto

@@ -28,6 +28,8 @@ enum Source {
 }
 
 message PersonList { repeated Person person = 1; }
+message GameList { repeated Game games = 1; }
+
 // Authentication messages
 message LoginRequest {
   string username = 1;
@@ -63,6 +65,7 @@ service AuthService {
 }
 
 message GameRequest { string title = 1; }
+message GetGamesRequest {}
 
 message AddOpinionRequest {
   string game_title = 1;
@@ -71,6 +74,7 @@ message AddOpinionRequest {
 
 service MainService {
   rpc GetGame(GameRequest) returns (Game);
+  rpc GetGames(GetGamesRequest) returns (GameList);
   rpc AddGame(Game) returns (Game);
   rpc AddOpinion(AddOpinionRequest) returns (Person);
 }