chore(examples): remove obsolete Omniglot script

[moriyaya]

Summary

• remove the obsolete meta_learning_omniglot.py example;
• retain the maintained sinusoid and Omniglot meta-learning examples.

Rationale

The removed script is not referenced by the README or test suite and cannot run with the current BOAT API. It contains user-specific and invalid absolute paths, omits required optimizer configuration, and calls outdated solver-building interfaces. Keeping it could mislead users attempting to reproduce the examples.

Validation

• confirmed that no tracked source references the deleted filename;
• syntax-checked the remaining meta-learning scripts without generating bytecode files;
• reviewed the PR to ensure that it contains no unrelated changes.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.17%. Comparing base (23895bb) to head (6f5b359).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #96   +/-   ##
=======================================
  Coverage   99.17%   99.17%           
=======================================
  Files          31       31           
  Lines        1206     1206           
=======================================
  Hits         1196     1196           
  Misses         10       10           

Flag	Coverage Δ
unittests	99.17% <ø> (ø)

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[callous-youth]

Reviewed and approved.

[callous-youth]

Reviewed and approved.