Fix locale bug and parkour spawn position

- Fix locale 'true' bug with sanitization at all levels:
  * ConfigAccessor.getString() - force String.valueOf()
  * Option.java - sanitize LANG defaults from config
  * PlayerSettingsManager - sanitize on settings load
  * SQLDataMapper - sanitize on SQL load
  * StorageDisk - sanitize on JSON load
  * SQLMigrationManager - SQL migration to fix DB

- Fix parkour first block position:
  * Island.java - spawn 6 blocks forward + 1 up from center
  * GeneratorCleanup.java - same position after fall/reset

- Add spawn-location config option at top of config.yml

src/main/java/dev/loki/loparkour/config/Option.java

@@ -266,6 +266,12 @@ public class Option {
                 // Always read as String to avoid Boolean parsing issues
                 String value = Config.CONFIG.getString(defaultPath);
 
+                // Sanitize legacy Boolean values for LANG option
+                if (option == ParkourOption.LANG && ("true".equals(value) || "false".equals(value) || "1".equals(value) || "0".equals(value))) {
+                    value = "en";
+                    LoParkour.getPlugin().getLogger().warning("LANG option had invalid Boolean value, reset to 'en'");
+                }
+
                 // Debug logging
                 if (option == ParkourOption.LANG) {
                     LoParkour.getPlugin().getLogger().info("LANG option: path=" + defaultPath + ", value=" + value);