25 path 01 shortest path solver bfs

[OnixTech]

Summary

Implements a BFS shortest-path solver from the maze entry to the exit and exposes the path as a sequence of N/E/S/W directions.

Fixes #25

Changes

• Added shortest path search from entry to exit.
• Exposed the result trough the shortest_path property.
• Added the shortest-path output to the exported maze file.
• Added test for seed reproducibility, maze regeneration, and the expected shortest path.

Testing

• make lint passes locally
• make test passes locally
• Manually tested the behavior described above

Checklist

• PR title follows <TICKET-ID>: short description
• Linked to the correct issue (Fixes #... above)
• No unrelated changes bundled into this diff
• [] Updated README if this changes user-facing behavior (config keys, controls, etc.)

[semere-meb]

Clean. BFS is simple and it guarantees the shortest path for our maze (since it is unweighted).