Remove ordered-set dependency

[Singhom931]

Summary

• Replace OrderedSet usage with insertion-ordered dictionaries.
• Preserve insertion order and prevent duplicate limits and endpoint hints.
• Remove the ordered-set dependency from pyproject.toml and uv.lock.

Testing

• uv run pytest tests/test_decorators.py tests/test_blueprints.py — 48 passed.
• uv lock --check — passed.
• git diff --check — passed.
• The full test suite could not be completely verified because Docker Compose was unavailable for Docker-dependent integration tests.

Closes #492

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (0e715b6) to head (72cdfd5).

Additional details and impacted files

@@            Coverage Diff            @@
##            master      #499   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           10        10           
  Lines         1006      1005    -1     
=========================================
- Hits          1006      1005    -1     

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