The victory hatch (maze[y][x]==2) is now chosen among all walkable cells
at Chebyshev distance >= MIN_GOAL_DIST (3) from the player start (1,1),
instead of being constrained to the bottom row. This lets the goal appear
anywhere in the maze while always staying far from the start.
- maze.c: collect all floor cells with chebyshev(1,1) >= 3 and pick one
at random; fallback to the farthest floor cell if none qualifies.
- doc/generation.md + report: document the new placement rule.
enne2
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