chore(rust): switch to validating mlt-nom variant

[nyurik]

The rust/mlt branch is no longer capable of parsing current data format, and should be migrated to the newer rust/mlt-nom implementation. For now, I renamed rust.yml into rust-legacy.yml, which at some point will be deleted.

[Copilot]

Pull Request Overview

This PR migrates the Rust CI workflow from the legacy rust/mlt implementation to the newer rust/mlt-nom variant. The original workflow is preserved as rust-legacy.yml for potential future reference, while rust.yml is updated to use the mlt-nom directory.

Key Changes:

• Updated rust.yml to point all jobs to ./rust/mlt-nom working directory
• Created rust-legacy.yml preserving the original workflow pointing to ./rust/mlt

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
.github/workflows/rust.yml	Updated working directory from ./rust/mlt to ./rust/mlt-nom across all three jobs (test, test-msrv, coverage)
.github/workflows/rust-legacy.yml	New file preserving the original workflow configuration pointing to ./rust/mlt

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 57.34%. Comparing base (b8e0f4a) to head (ee74170).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #610      +/-   ##
==========================================
- Coverage   65.59%   57.34%   -8.25%     
==========================================
  Files          19       30      +11     
  Lines        1735     2288     +553     
  Branches     1735     2288     +553     
==========================================
+ Hits         1138     1312     +174     
- Misses        556      878     +322     
- Partials       41       98      +57     

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