Holiday switch in the debug menu; darker wood for the treasury chests

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/settings.rs

@@ -159,6 +159,7 @@ pub struct Settings {
     pub debug_trigger_zones: bool,       // draw mission trigger zones
     pub debug_command_markers: bool,     // draw extra command markers (guard/attack/gather stay fixed)
     pub debug_path_lines: bool,          // draw creature path lines
+    pub debug_holiday: u8,               // holiday: 0 by the date, 1 none, 2 Halloween, 3 Christmas, 4 Easter
     // game
     pub game_speed: f32, // 1 or 2
     pub hints: bool,
@@ -200,6 +201,7 @@ impl Default for Settings {
             debug_trigger_zones: false,
             debug_command_markers: false,
             debug_path_lines: false,
+            debug_holiday: 0,
             game_speed: 1.0,
             hints: true,
             difficulty: 1,