Add 2D Asset Pipeline example

[yenatempest]

Adds the 2D Asset Pipeline workspace example — pixel art sprite and animation generation, fully local.

What's included:

• workspace.yml + workspace.lock
• Two user agents: file-saver and spritesheet-normalizer
• README.md
• Assets: output.png, single-asset.png, animation.png
• examples.json entry

Two workflows:

• Single asset — HTTP trigger → generate PNG → chroma-key background removal → nearest-neighbour resize → saved to ~/game_assets
• Animation — HTTP trigger → generate spritesheet → normalize frames → assemble looping GIF → resize → saved to ~/game_assets. Includes a regeneration loop if the spritesheet normalizer cannot parse frame boundaries.

User agents verified: file-saver and spritesheet-normalizer both have valid metadata.json, agent: values match folder names, and all FSM agentId refs resolve. Compatible with the bundle import path in Discover Spaces.

One install dep: brew install imagemagick — noted in the README setup section.