Feat/openapi pydantic native

[NEFORCEO]

🚀 Description

Rebuilds OpenAPI schema generation entirely on Pydantic's own JSON Schema
generation (model_json_schema() / TypeAdapter / models_json_schema())
instead of a hand-written type mapper, and adds several Swagger UI /
docs features on top of it.

OpenAPI generator (fasthttp/openapi/generator.py)

• Replaced manual type→schema mapping with Pydantic-native generation:
  enums, unions/Optional, constraints, defaults, and nested models are
  now handled correctly instead of falling back to {"type": "string"}.
• Nested/shared models are deduplicated via models_json_schema() and
  merged into components/schemas with proper $ref rewriting.
• Field descriptions from Field(description=...) now come through
  natively; Doc(...) annotations (the project's existing docstring
  convention) are still backfilled where Pydantic has no description.
• Query params and raw json=/data= bodies now surface their literal
  values as OpenAPI examples, so Swagger UI's "Try it out" pre-fills them.
• Routes without explicit tags are now grouped by hostname instead of
  a single "Default" bucket.

Swagger UI / docs (fasthttp/openapi/swagger.py, fasthttp/app.py, fasthttp/openapi/urls.py)

• New /redoc endpoint (ReDoc — read-only alternative view).
• Proper dark theme for Swagger UI, targeting the real swagger-ui-dist
  classes (previous approach used a filter: invert() hack that
  distorted method-color badges, logos, and the JSON viewer).
• persistAuthorization, requestSnippetsEnabled, and filter enabled
  in the Swagger UI config.
• /request proxy now returns response timing (x-fasthttp-duration-ms),
  visible in the Swagger UI response headers panel.
• 404 page now links to /redoc alongside /docs and /openapi.json.

Bug fix (fasthttp/routing.py)

• Route.response_model was typed as type | None, which made Pydantic
  reject response_model=list[Model] at route-registration time — a
  pattern used throughout examples/ and docs/. Widened to Any.

Docs

• docs/en/openapi.md, docs/ru/openapi.md, and the OpenAPI Swagger UI
  tutorial pages updated with the new /redoc endpoint and dark mode
  screenshots. README updated with the same screenshots.
• New example: examples/openapi/pydantic_schema_example.py demonstrating
  enums, nested models, Field descriptions/examples, and error models.

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🧩 Type of Change

• feat: New feature
• fix: Bug fix
• docs: Documentation update
• refactor: Code refactoring
• ci: CI/CD changes
• chore: Maintenance

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✅ Checklist

• Tests added or updated (tests/test_openapi.py rewritten against the
  new _SchemaCollector API; full suite passes — 564 passed)
• Documentation updated (README, docs/en, docs/ru, tutorial pages)
• No breaking changes (only private, unexported generator.py helpers
  were renamed/removed; public API — generate_openapi_schema,
  get_swagger_html, get_not_found_html, etc. — is unchanged aside
  from the additive redoc_url parameter)
• Code follows project style

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🔗 Related Issues

Fixes #

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📸 Additional Context

New screenshots: docs/photo/swagger_dark.png, docs/photo/redoc.png.

Manually verified locally: /docs, /redoc, /openapi.json all serve
200 with examples/openapi/pydantic_schema_example.py; generated schema
inspected for enum $refs, nested model dedup, and example prefill.

[github-actions]

👋 Thanks for your contribution, @NEFORCEO!

Please make sure:

• Code is clean and formatted
• Tests are passing
• PR description is clear

Maintainers will review it soon.

[codspeed-hq]

Merging this PR will improve performance by 40.35%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 6 improved benchmarks
✅ 6 untouched benchmarks

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
⚡	test_response_req_text_from_json	213.2 µs	134.7 µs	+58.25%
⚡	test_response_repr	196.4 µs	134.2 µs	+46.43%
⚡	test_response_property_access	194.5 µs	135.2 µs	+43.82%
⚡	test_response_json_parsing	205.6 µs	144.7 µs	+42.04%
⚡	test_response_creation	201.3 µs	142.6 µs	+41.19%
⚡	test_middleware_after_response	403.1 µs	352.5 µs	+14.35%

Tip

Curious why this is faster? Comment @codspeedbot explain why this is faster on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing feat/openapi-pydantic-native (ce89aca) with master (6f3d441)¹}

Footnotes

1. No successful run was found on master (de5b998) during the generation of this report, so 6f3d441 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩