Add initial Pico-8 cartridges for testing

- Created test_cart.p8 with basic drawing functionality and a print statement.
- Created test_unix.p8 with a simple initialization function.

scripts/core/TileSet.js

@@ -0,0 +1,167 @@
+/**
+ * Represents a single tileset with 8x8 tiles (128x128px total, 16x16 grid).
+ */
+export class TileSet {
+  /**
+   * @param {Object} options Configuration options.
+   * @param {string} options.id Unique identifier.
+   * @param {string} options.name Display name.
+   * @param {string} options.filePath Path or URL to PNG file (file:// or blob:).
+   * @param {string} [options.nativePath] Native file system path (for Electron).
+   * @param {number} [options.tileWidth=8] Tile width in pixels.
+   * @param {number} [options.tileHeight=8] Tile height in pixels.
+   * @param {number} [options.columns=16] Number of tiles per row (128px / 8px = 16).
+   * @param {number} [options.rows=16] Number of tile rows (128px / 8px = 16).
+   */
+  constructor(options) {
+    this.id = options.id || this.#generateId();
+    this.name = options.name || "Untitled Tileset";
+    this.filePath = options.filePath || "";
+    this.nativePath = options.nativePath || "";
+    this.tileWidth = options.tileWidth || 8;
+    this.tileHeight = options.tileHeight || 8;
+    this.columns = options.columns || 16;
+    this.rows = options.rows || 16;
+    
+    /** @type {HTMLImageElement | null} */
+    this.image = null;
+    
+    /** @type {boolean} */
+    this.isLoaded = false;
+  }
+
+  /**
+   * Generates a unique identifier.
+   *
+   * @returns {string}
+   */
+  #generateId() {
+    return `tileset_${Date.now()}_${Math.random().toString(36).substring(2, 9)}`;
+  }
+
+  /**
+   * Gets the total number of tiles.
+   *
+   * @returns {number}
+   */
+  getTileCount() {
+    return this.columns * this.rows;
+  }
+
+  /**
+   * Gets the total width of the tileset image.
+   *
+   * @returns {number}
+   */
+  getWidth() {
+    return this.columns * this.tileWidth;
+  }
+
+  /**
+   * Gets the total height of the tileset image.
+   *
+   * @returns {number}
+   */
+  getHeight() {
+    return this.rows * this.tileHeight;
+  }
+
+  /**
+   * Loads the tileset image from file path.
+   *
+   * @returns {Promise<void>}
+   */
+  async load() {
+    if (!this.filePath) {
+      throw new Error("No file path specified");
+    }
+
+    return new Promise((resolve, reject) => {
+      const img = new Image();
+      
+      img.onload = () => {
+        // Validate image is exactly 128x128px
+        if (img.width !== 128 || img.height !== 128) {
+          reject(new Error(`Tileset must be exactly 128x128px (found ${img.width}x${img.height}px)`));
+          return;
+        }
+        
+        this.image = img;
+        this.isLoaded = true;
+        
+        // Fixed grid: 16x16 tiles for 128x128 image with 8x8 tiles
+        this.columns = 16;
+        this.rows = 16;
+        
+        resolve();
+      };
+      
+      img.onerror = () => {
+        reject(new Error(`Failed to load image: ${this.filePath}`));
+      };
+      
+      // Add cache-busting for file:// URLs to ensure reload works
+      const cacheBuster = this.filePath.startsWith("file://") 
+        ? `?t=${Date.now()}` 
+        : "";
+      img.src = this.filePath + cacheBuster;
+    });
+  }
+
+  /**
+   * Reloads the tileset image.
+   *
+   * @returns {Promise<void>}
+   */
+  async reload() {
+    this.isLoaded = false;
+    this.image = null;
+    return this.load();
+  }
+
+  /**
+   * Gets tile coordinates for a specific tile index.
+   *
+   * @param {number} tileIndex Tile index (0-based).
+   * @returns {{x: number, y: number, width: number, height: number}}
+   */
+  getTileRect(tileIndex) {
+    const col = tileIndex % this.columns;
+    const row = Math.floor(tileIndex / this.columns);
+    
+    return {
+      x: col * this.tileWidth,
+      y: row * this.tileHeight,
+      width: this.tileWidth,
+      height: this.tileHeight
+    };
+  }
+
+  /**
+   * Serializes tileset to JSON.
+   *
+   * @returns {Object}
+   */
+  toJSON() {
+    return {
+      id: this.id,
+      name: this.name,
+      filePath: this.filePath,
+      nativePath: this.nativePath,
+      tileWidth: this.tileWidth,
+      tileHeight: this.tileHeight,
+      columns: this.columns,
+      rows: this.rows
+    };
+  }
+
+  /**
+   * Creates tileset from JSON data.
+   *
+   * @param {Object} data Serialized tileset.
+   * @returns {TileSet}
+   */
+  static fromJSON(data) {
+    return new TileSet(data);
+  }
+}