fix: added minigames description to Gemini.md, fixed song end note, fixed custom songs not loading, added another test song

GEMINI.md

@@ -51,4 +51,107 @@ Based on the analysis of `impostor.lua`, the following regularities and conventi
 
 ## Agent Directives
 
-- **Git Operations:** In the future, do not perform `git add` or `git commit` operations. This responsibility will be handled by the user.
+- **Git Operations:** In the future, do not perform `git add` or `git commit` operations. This responsibility will be handled by the user.
+
+---
+
+# Impostor Minigames Documentation
+
+This document provides comprehensive documentation for all three minigames implemented in the Impostor game: Button Mash, Rhythm, and DDR (Dance Dance Revolution).
+
+## Table of Contents
+
+- [Overview](#overview)
+- [Button Mash Minigame](#button-mash-minigame)
+- [Rhythm Minigame](#rhythm-minigame)
+- [DDR Minigame](#ddr-minigame)
+- [Integration Guide](#integration-guide)
+- [Common Features](#common-features)
+
+---
+
+## Overview
+
+The Impostor game includes three interactive minigames that can be triggered during gameplay. Each minigame presents a unique challenge that the player must complete to progress. All minigames feature:
+
+- **Overlay rendering** - Minigames render over the current game window
+- **Progress tracking** - Visual indicators show completion status
+- **Return mechanism** - Automatic return to the calling window upon completion
+- **Visual feedback** - Button presses and hits are visually indicated
+
+---
+
+## Button Mash Minigame
+
+**File**: `inc/window/window.minigame.mash.lua`
+
+### Description
+
+A fast-paced minigame where the player must repeatedly press the Z button to fill a progress bar. The bar automatically degrades over time, and the degradation rate increases as the bar fills up, creating increasing difficulty.
+
+### Gameplay Mechanics
+
+- **Objective**: Fill the progress bar to 100% by pressing Z repeatedly
+- **Challenge**: The bar degrades automatically, with degradation increasing as it fills
+- **Win Condition**: Bar reaches 100%
+- **No Fail State**: Player can keep trying until successful
+
+### Visual Elements
+
+#### Simple sketch
+![button_mash.png](/button_mash.png)
+
+```
+Progress Bar (200x12px at 20,10):
+┌────────────────────────────────────┐
+│████████████████░░░░░░░░░░░░░░  45%│
+└────────────────────────────────────┘
+
+Button Indicator (Bottom):
+╔═══╗
+║ Z ║  ← Press repeatedly!
+╚═══╝
+
+Text: "MASH Z!"
+```
+
+#### Configuration Parameters
+
+```lua
+bar_fill = 0                    -- Current fill level (0-100)
+max_fill = 100                  -- Target fill level
+fill_per_press = 8              -- Points gained per button press
+base_degradation = 0.15         -- Base degradation per frame
+degradation_multiplier = 0.006  -- Increases degradation with bar fill
+button_press_duration = 8       -- Visual feedback duration (frames)
+```
+
+#### Usage Example
+
+```lua
+-- Start button mash minigame
+MinigameButtonMashWindow.start(WINDOW_GAME)
+
+-- Or from any window
+MinigameButtonMashWindow.start(WINDOW_POPUP)
+```
+
+#### Color Coding
+
+- **Green**: Low fill (0-33%)
+- **Medium (NPC color)**: Medium fill (34-66%)
+- **Yellow (Item color)**: High fill (67-100%)
+
+---
+
+## Rhythm Minigame
+
+**File**: `inc/window/window.minigame.rhythm.lua`
+
+### Description
+
+A timing-based minigame where the player must press Z when a moving line crosses a green target zone. The target zone shrinks with each successful hit, making the game progressively more challenging.
+
+### Gameplay Mechanics
+
+- **Objective**: Score 10 points by timing button presses correctly