Per-world Creeper settings complete

- Added per-world Block Damage settings
- Added per-world Entity Damage settings
- Added creeper_settings database support
- Added world-specific Creeper menus
- Added automatic world registration/default inheritance
- Split Creeper listeners
- Updated Creeper behavior to use world settings
- Removed obsolete global Creeper indicators
- Adopted logger-based error reporting standard

src/main/java/com/rsscripting/serveradmin/dao/SettingsDAO.java

@@ -0,0 +1,135 @@
+package com.rsscripting.serveradmin.dao;
+
+import com.rsscripting.serveradmin.database.DatabaseManager;
+import com.rsscripting.serveradmin.settings.SettingKey;
+
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+
+public class SettingsDAO {
+
+    private final DatabaseManager databaseManager;
+
+    public SettingsDAO(DatabaseManager databaseManager) {
+        this.databaseManager = databaseManager;
+    }
+
+    public void initializeDefaults() throws SQLException {
+
+        for (SettingKey key : SettingKey.values()) {
+
+            if (!defaultExists(key)) {
+
+                boolean value = getDefaultValue(key);
+
+                setDefault(key, value);
+            }
+        }
+    }
+
+    private boolean defaultExists(SettingKey key) throws SQLException {
+
+        Connection connection = databaseManager.getConnection();
+
+        try (PreparedStatement statement = connection.prepareStatement(
+                "SELECT setting_key FROM defaults WHERE setting_key = ?")) {
+
+            statement.setString(1, key.name());
+
+            try (ResultSet rs = statement.executeQuery()) {
+                return rs.next();
+            }
+        }
+    }
+
+    private boolean getDefaultValue(SettingKey key) {
+
+        return switch (key) {
+
+            case KEEP_INVENTORY -> true;
+
+            case CREEPER_BLOCK_DAMAGE,
+                 CREEPER_ENTITY_DAMAGE,
+                 KEEP_INVENTORY_NEW_WORLD -> false;
+
+        };
+    }
+
+    public void setDefault(
+            SettingKey key,
+            boolean value
+    ) throws SQLException {
+
+        Connection connection = databaseManager.getConnection();
+
+        try (PreparedStatement statement = connection.prepareStatement(
+                """
+                INSERT OR REPLACE INTO defaults
+                (setting_key, value)
+                VALUES (?, ?)
+                """
+        )) {
+
+            statement.setString(1, key.name());
+            statement.setInt(2, value ? 1 : 0);
+
+            statement.executeUpdate();
+        }
+
+    }
+
+    public boolean getDefault(
+            SettingKey key
+    ) throws SQLException {
+
+        Connection connection =
+                databaseManager.getConnection();
+
+        try (PreparedStatement statement =
+                     connection.prepareStatement(
+                             """
+                             SELECT value
+                             FROM defaults
+                             WHERE setting_key = ?
+                             """
+                     )) {
+
+            statement.setString(
+                    1,
+                    key.name()
+            );
+
+            try (ResultSet rs =
+                         statement.executeQuery()) {
+
+                if (rs.next()) {
+
+                    return rs.getInt("value") == 1;
+
+                }
+
+            }
+
+        }
+
+        return false;
+
+    }
+
+    public void toggleDefault(
+            SettingKey key
+    ) throws SQLException {
+
+        boolean current =
+                getDefault(key);
+
+        setDefault(
+                key,
+                !current
+        );
+
+    }
+
+}