21: maze displayed from adapter

[semere-meb]

Summary

Renders the maze generated from Adapter.

Fixes #21

Changes

• New MazeView class to render the maze
• New Settings class to hold tunable design choices
• Replace arcade with mlx to display the graphics (conforming to the subject)
• flake.nix updated to pass through necessary libraries for mlx

Testing

• make lint passes locally
• make test passes locally (check N/A below if no tests exist yet for this area)
• Manually tested the behavior described above
• N/A — no automated tests apply to this change yet

Checklist

• PR title follows <TICKET-ID>: short description
• Linked to the correct issue (Fixes #... above)
• No unrelated changes bundled into this diff
• Updated docs/design/ if this changes config shape, architecture, or a game-design decision
• Updated README if this changes user-facing behavior (config keys, controls, etc.)