[Daxia] [ FastAPI ] Fix encoders.py bytes and memoryview handling

[daxia778]

/claim #759

Summary

• Encodes bytes and memoryview as base64 strings by default in jsonable_encoder.
• Adds bytes_encoding="hex" for hexadecimal output and validates unsupported values.
• Propagates the bytes encoding option through nested containers, dataclasses, Pydantic models, and fallback object encoding.
• Adds regression coverage for raw bytes, memoryview, nested values, Pydantic model bytes fields, and a FastAPI JSON response.
• Adds _provenance.json with private runtime instructions redacted.

Demo

https://github.com/daxia778/Bounty-Hunters/releases/download/issue-759-demo-d1759cdc/fastapi-bytes-759-demo-d1759cdc.mp4

Validation

• uv run pytest tests/test_jsonable_encoder.py -q -> 32 passed, 1 skipped
• uv run ruff check fastapi/encoders.py tests/test_jsonable_encoder.py
• uv run ruff format --check fastapi/encoders.py tests/test_jsonable_encoder.py
• python3 -m json.tool fastapi/_provenance.json >/dev/null && git diff --check

Fixes #759

[github-actions]

Unfortunately the changes in this PR didn't fully resolve the issue. Please rework your solution and submit a new pull request.

Make sure to review the acceptance criteria in the linked issue and verify all conditions are met before resubmitting. See CONTRIBUTING.md for guidelines.