Fix/ssrf secrets openapi

[NEFORCEO]

x## 🚀 Description

Fixes a handful of correctness and security bugs found during a repo audit:

• openapi/generator.py: BasicAuth/BearerAuth/DigestAuth/OAuth2ClientCredentials were imported only under TYPE_CHECKING but used at runtime in isinstance() checks — this raised NameError whenever OpenAPI generation hit a route with auth set. Moved the import to module level.
• security/ssrf.py: check_url() failed open (allowed the request) when DNS resolution raised socket.gaierror. Changed to fail closed (block), consistent with the other exception branch.
• security/secrets.py: SecretsMasking.mask_url() was a no-op in the pure-Python fallback (no compiled fasthttp._core), silently leaving secrets in query strings (?api_key=..., ?token=...) unmasked. Implemented a real fallback using the existing SECRET_PARAM_REGEX.
• app.py: split _run_sse into _run_sse (reconnect/backoff loop) + _stream_sse (connection + event parsing) to remove duplicated retry code and drop cyclomatic complexity below the lint threshold; narrowed the blind except Exception with an explicit # noqa: BLE001.
• routing.py: added # noqa: TC001 to the auth import — it looks type-only to ruff, but Route is a pydantic model and the field is resolved at runtime, so the import can't move into TYPE_CHECKING.
• response.py: removed an unused httpx import; moved datetime under TYPE_CHECKING (used only in annotations).
• dependencies/dependencies.py: minor comment cleanup.
• Removed a stray duplicate file, examples/middleware/retry_middleware 2.py.

No documentation changes in this PR.

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🧩 Type of Change

Please select one:

• 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
• Documentation updated
• No breaking changes
• Code follows project style

ruff check fasthttp/ is clean and the full test suite passes (559 passed).

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🔗 Related Issues

Fixes #

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📸 Additional Context

Found via a manual security/lint audit of fasthttp/, not tied to a filed issue. The openapi/generator.py and security/secrets.py fixes are the most impactful — both are silent runtime bugs with no existing test coverage.

[github-actions]

👋 Thanks for your contribution, @NEFORCEO!

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

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[codspeed-hq]

Merging this PR will improve performance by 42.38%

⚠️ 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	135.3 µs	+57.56%
⚡	test_response_repr	196.4 µs	131.6 µs	+49.22%
⚡	test_response_property_access	194.5 µs	131.2 µs	+48.25%
⚡	test_response_json_parsing	205.6 µs	141.6 µs	+45.22%
⚡	test_response_creation	201.3 µs	140.3 µs	+43.49%
⚡	test_middleware_after_response	403.1 µs	351.4 µs	+14.71%

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 fix/ssrf-secrets-openapi (3b65f26) with master (6f3d441)¹}

Footnotes

1. No successful run was found on master (e7a0dd8) 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. ↩