Add CodSpeed performance benchmarks and CI integration

[codspeed-hq]

Summary

This PR sets up CodSpeed continuous performance testing for starlette-admin. It adds a suite of benchmarks covering the most frequently exercised, CPU-bound code paths and wires up a GitHub Actions workflow to run them on every push and pull request.

Changes

• benchmarks/test_benchmarks.py — 10 pytest-codspeed benchmarks targeting pure-CPU, deterministic code paths that need no database, network or event loop:
  • helpers: prettify_class_name, slugify_class_name, get_file_icon, html_params, extract_fields
  • fields: field construction, StringField.input_params, BaseField.dict() serialization
  • converters: StandardModelConverter.convert_fields_list and converter lookup
• .github/workflows/codspeed.yml — GitHub Actions workflow running the benchmarks with CodSpeedHQ/action@v4 in simulation mode, authenticated via OpenID Connect (no token required).
• README.md — Added the CodSpeed badge.

Notes

• The benchmarks use the CPU simulation instrument (the default for Python), which provides hardware-agnostic, low-variance measurements and automatic flamegraphs.
• The workflow installs the package together with pytest and pytest-codspeed, keeping the benchmark job lightweight and independent from the heavier ORM test matrix.
• All benchmarks were verified locally in simulation mode and pass the repository's ruff and black checks.

Next steps

• Once merged, CodSpeed will establish a performance baseline from the main branch and report deltas on subsequent pull requests.
• Additional benchmarks can be added over time to cover more code paths (e.g. async serialization, ORM-specific converters) as needed.

[github-actions]

🚀 Deployed on https://docs-preview-775--starlette-admin-docs-preview.netlify.app

[codspeed-hq]

Congrats! CodSpeed is installed 🎉

🆕 10 new benchmarks were detected.

You will start to see performance impacts in the reports once the benchmarks are run from your default branch.

Detected benchmarks

• test_convert_fields_list: 349.9 µs
• test_extract_fields: 125 µs
• test_field_construction: 107.7 µs
• test_field_dict_serialization: 84.1 µs
• test_get_converter_lookup: 25.5 µs
• test_get_file_icon: 62.3 µs
• test_html_params: 60.6 µs
• test_prettify_class_name: 51.1 µs
• test_slugify_class_name: 33.1 µs
• test_string_field_input_params: 59.2 µs

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (e4868ce) to head (2280850).

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #775   +/-   ##
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  Coverage   100.00%   100.00%           
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  Files           86        86           
  Lines         6848      6848           
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  Hits          6848      6848           

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