feat: add total player count and total playtime logic

- Implemented TotalPlayerCountLogic to retrieve the total number of unique players within a specified time range.
- Implemented TotalPlayTimeLogic to calculate the total playtime of players within a specified time range.
- Created ServiceContext to manage database connections and initialize necessary tables.
- Added types for total player count and total playtime requests and responses.
- Set up the main server file to start the application with the necessary configurations.
- Updated go.mod and go.sum for new dependencies.

app/internal/config/config.go

@@ -0,0 +1,12 @@
+package config
+
+import "github.com/zeromicro/go-zero/rest"
+
+type Config struct {
+	rest.RestConf
+	Database DatabaseConfig
+}
+
+type DatabaseConfig struct {
+	DSN string // Data Source Name for database connection
+}