feat(bytesbuf): improve ergonomics of BytesView::as_read()

[sandersaares]

Summary

This PR now simplifies the bytesbuf read path by removing the BytesViewReader wrapper and implementing std::io::Read and std::io::BufRead directly on BytesView.

What changed

bytesbuf functional changes

• BytesViewReader was removed.
• Read and BufRead are implemented directly for BytesView.
• BytesView::reader() was removed.
• The old read_adapter.rs module was renamed to view_read.rs to match its contents.
• bytesbuf docs were updated to describe direct Read/BufRead support on BytesView.

Repository maintenance changes included in this branch

• Ran just format (format-only updates across the repository).
• Ran just readme and committed generated README updates.
• Updated AGENTS.md with README/format guidance and a pre-commit checklist.

Validation

• cargo clippy -p bytesbuf --all-features -- -D warnings
• cargo test -p bytesbuf --all-features
  • 156 unit tests passed
  • 59 doc-tests passed

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.0%. Comparing base (5cae290) to head (38a7472).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #272   +/-   ##
=======================================
  Coverage   100.0%   100.0%           
=======================================
  Files         141      141           
  Lines        8626     8626           
=======================================
  Hits         8626     8626           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[github-actions]

⚠️ Breaking Changes Detected

--- failure inherent_method_missing: pub method removed or renamed ---

Description:
A publicly-visible method or associated fn is no longer available under its prior name. It may have been renamed or removed entirely.
        ref: https://doc.rust-lang.org/cargo/reference/semver.html#item-remove
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.46.0/src/lints/inherent_method_missing.ron

Failed in:
  BytesView::as_read, previously in file /home/runner/work/oxidizer/oxidizer/target/semver-checks/git-origin_main/72cc20df072573a1a83bb56bfb2859b7206b7666/crates/bytesbuf/src/view.rs:737

If the breaking changes are intentional then everything is fine - this message is merely informative.

Remember to apply a version number bump with the correct severity when publishing a version with breaking changes (1.x.x -> 2.x.x or 0.1.x -> 0.2.x).