fix(maps): repair non-enterable authored exits

[zoeyrose]

Summary

Repair the current authored map changes that remove the statically detected
non-enterable exit destinations from the content corpus. This addresses the
content-repair work tracked by content#256
and is separate from the strict validator gate in
content#258.

The nine modified maps remove 28 of the 30 findings currently reported by the
strict scan. The two remaining edge-stair findings depend on restoring
filename-based automatic tiling in
classic#525 and are documented
below rather than hidden by this PR.

Implementation / behavior

• Mark decorative or intentionally non-tiled stair and ladder records with
  last_heal 0 so they do not inherit an automatic tiled-exit destination.
• Remove the stale Hall of DMs exit to the obsolete Tutorial Island location
  and its associated sign.
• Preserve the authored map layouts while updating modified dates and the
  canonical ordering of affected metadata records.
• Exclude editor scratch directories and all unrelated working-tree files.

Validation

• python3 tools/validate_exits.py --json — reports exactly two remaining
  diagnostics, both the filename-tiling edge cases listed below.
• python3 tools/validate.py — content parsing, release parity, and 175 tests
  pass; the current main baseline then rejects 28 stale baseline entries,
  which is expected to disappear when strict validator PR fix(validation): enforce strict authored exit checks #258 removes the
  baseline mechanism.
• git diff --check — passed.

Limitations / follow-up

The following two findings intentionally remain until Classic automatic tiling
is restored and the validator is aligned with that runtime behavior:

• /shattered_islands/world_1_50:2571, (19,23), facing south, resolves to
  /shattered_islands/world_1_50_-1 at (19,24).
• /shattered_islands/world_2_47:105, (0,15), facing west, resolves to
  /shattered_islands/world_2_47_-1 at (-1,15).

This draft should converge with classic#525
and content#258 before the strict
content gate is expected to report zero findings.

Refs content#256