sim/mujoco: list_urdfs column width / wrapping on narrow terminals (T53)

[cagataycali]

Cosmetic follow-up from PR #85 review.

list_urdfs prints an ASCII table of the 68 registered robots. With long data_config keys and long paths, the columns can wrap on narrow terminals and look ragged.

DoD

• Decide on a target terminal width (80 or 100 chars) and truncate the path column to fit.
• Add a visual / snapshot test pinning the format so we don't regress.
• Optional: support --full to disable truncation.

Low priority — purely presentational. Tracked per AGENTS.md rule (board is source of truth for follow-ups).

[cagataycali]

Fixed in PR #85 (commit 7d9a0d9).

What changed:

• format_robot_table() gained an optional max_width parameter (default 100).
• Descriptions get truncated with an ellipsis when a row would overflow.
• Width constants named (_NAME_WIDTH, _CAT_WIDTH, ...) so tests can assert against them.
• Drive-by: the aerial category was missing from the iteration order so drones (crazyflie, skydio_x2) never showed up even though they were fully registered.

Tests: new tests/registry/test_format_robot_table.py — 8 tests covering default width, narrow width (80-col), wide width (1000), row-count consistency.