feat: add experimental tileset catalog

[jasoncavinder]

Summary

• add an experimental, read-only tileset identity/name catalog to the core
  library
• add tilewright tilesets <PATH> with deterministic human and versioned JSON
  output
• preserve modes, image slots, flags, notes, and unknown fields only in the raw
  snapshot
• record the evidence contract and accepted ADR 0012

Evidence and impact

The bounded audit covers 24 tileset records and 196 resolving map references
across four RPG Maker MZ 1.10.0 projects. An independent comparison matched all
72 projected and CLI-envelope values. This does not validate map references,
assets, tile behavior, mutation, persistence, or later versions.

Verification

• generated synthetic structural, boundary, preservation, and CLI tests
• independent four-project differential audit
• complete Rust workspace quality gate passed locally
• git diff --check passed

[jasoncavinder]

Resolved the merge conflicts with current dev and pushed remediation commit eece11a.

What changed:

• Preserved both the merged selected-map event capability and ADR 0011 and this PR tileset capability and ADR 0012 across the conflicted documentation.
• Restored the newer player-start differential evidence record during the final integration diff review.
• Fixed the Windows-only CI failure by comparing the diagnostic path against a native PathBuf instead of a hard-coded Unix separator.

Verification:

• Exact formerly failing CLI regression: passed.
• Full locked Rust quality gate: formatting, workspace check, all tests, clippy with warnings denied, and rustdoc with warnings denied all passed locally.
• Replacement GitHub checks: Ubuntu, macOS, Windows, aggregate Rust quality, PR policy, dependency review, and CodeQL all passed.

GitHub now reports the PR conflict-free and mergeable. It remains a draft only because its review state has not been changed.