Add cookbook and tutorial showcase demos

tests/demo/:
- cookbook_showcase.py: Interactive demo of cookbook recipes
- tutorial_showcase.py: Visual walkthrough of tutorial content
- tutorial_screenshots.py: Automated screenshot generation
- new_features_showcase.py: Demo of modern API features
- procgen_showcase.py: Procedural generation examples
- simple_showcase.py: Minimal working examples

Created during docs modernization to verify cookbook examples work.

🤖 Generated with Claude Code (https://claude.ai/code)

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

tests/demo/simple_showcase.py

@@ -0,0 +1,103 @@
+#!/usr/bin/env python3
+"""
+Simple Tutorial Screenshot Generator
+
+This creates ONE screenshot - the part01 tutorial showcase.
+Run with: xvfb-run -a ./build/mcrogueface --headless --exec tests/demo/simple_showcase.py
+
+NOTE: In headless mode, automation.screenshot() is SYNCHRONOUS - it renders
+and captures immediately. No timer dance needed!
+"""
+import mcrfpy
+from mcrfpy import automation
+import sys
+import os
+
+# Output
+OUTPUT_PATH = "/opt/goblincorps/repos/mcrogueface.github.io/images/tutorials/part_01_grid_movement.png"
+
+# Tile sprites from the labeled tileset
+PLAYER_KNIGHT = 84
+FLOOR_STONE = 42
+WALL_STONE = 30
+TORCH = 72
+BARREL = 73
+SKULL = 74
+
+def main():
+    """Create the part01 showcase screenshot."""
+    # Ensure output dir exists
+    os.makedirs(os.path.dirname(OUTPUT_PATH), exist_ok=True)
+
+    # Create scene
+    scene = mcrfpy.Scene("showcase")
+
+    # Load texture
+    texture = mcrfpy.Texture("assets/kenney_tinydungeon.png", 16, 16)
+
+    # Create grid - bigger zoom for visibility
+    grid = mcrfpy.Grid(
+        pos=(50, 80),
+        size=(700, 480),
+        grid_size=(12, 9),
+        texture=texture,
+        zoom=3.5
+    )
+    grid.fill_color = mcrfpy.Color(20, 20, 30)
+    scene.children.append(grid)
+
+    # Fill with floor
+    for y in range(9):
+        for x in range(12):
+            grid.at(x, y).tilesprite = FLOOR_STONE
+
+    # Add wall border
+    for x in range(12):
+        grid.at(x, 0).tilesprite = WALL_STONE
+        grid.at(x, 0).walkable = False
+        grid.at(x, 8).tilesprite = WALL_STONE
+        grid.at(x, 8).walkable = False
+    for y in range(9):
+        grid.at(0, y).tilesprite = WALL_STONE
+        grid.at(0, y).walkable = False
+        grid.at(11, y).tilesprite = WALL_STONE
+        grid.at(11, y).walkable = False
+
+    # Add player entity - a knight!
+    player = mcrfpy.Entity(
+        grid_pos=(6, 4),
+        texture=texture,
+        sprite_index=PLAYER_KNIGHT
+    )
+    grid.entities.append(player)
+
+    # Add decorations
+    for pos, sprite in [((2, 2), TORCH), ((9, 2), TORCH), ((2, 6), BARREL), ((9, 6), SKULL)]:
+        entity = mcrfpy.Entity(grid_pos=pos, texture=texture, sprite_index=sprite)
+        grid.entities.append(entity)
+
+    # Center camera on player
+    grid.center = (6 * 16 + 8, 4 * 16 + 8)
+
+    # Add title
+    title = mcrfpy.Caption(text="Part 1: The '@' and the Dungeon Grid", pos=(50, 20))
+    title.fill_color = mcrfpy.Color(255, 255, 255)
+    title.font_size = 28
+    scene.children.append(title)
+
+    subtitle = mcrfpy.Caption(text="Creating a grid, placing entities, handling input", pos=(50, 50))
+    subtitle.fill_color = mcrfpy.Color(180, 180, 200)
+    subtitle.font_size = 16
+    scene.children.append(subtitle)
+
+    # Activate scene
+    scene.activate()
+
+    # In headless mode, screenshot() is synchronous - renders then captures!
+    result = automation.screenshot(OUTPUT_PATH)
+    print(f"Screenshot saved: {OUTPUT_PATH} (result: {result})")
+    sys.exit(0)
+
+
+# Run it
+main()