fix(bytesbuf): correct put_bytes panic docs

[sandersaares]

BytesBuf::put_bytes documented an inapplicable panic condition (insufficient remaining capacity). Appending a BytesView is zero-copy and brings its own backing memory, so it never consumes buffer capacity; its only failure mode is the total length exceeding usize::MAX. The docs now state that.

While investigating, I also confirmed the usize bound only needs an explicit overflow guard on the BytesView side (already present in from_spans_reversed, documented on from_views/append/concat). BytesBuf::from_blocks / from_span_builders operate on exclusively owned memory (Block/SpanBuilder), whose combined capacity is bounded by the virtual address space and can never exceed usize::MAX. Added comments there explaining why no check is needed, contrasting with BytesView's shared, potentially aliased memory.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.9%. Comparing base (963e015) to head (375b4b5).

Additional details and impacted files

@@          Coverage Diff          @@
##            main    #496   +/-   ##
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  Coverage   99.9%   99.9%           
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  Files        336     336           
  Lines      24829   24829           
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  Hits       24818   24818           
  Misses        11      11           

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[Copilot]

Pull request overview

This PR corrects the public documentation for BytesBuf::put_bytes to describe its actual panic condition (length/capacity overflow), reflecting that appending a BytesView is zero-copy and does not require remaining writable capacity in the buffer.

Changes:

• Update BytesBuf::put_bytes panic docs to describe overflow (> usize::MAX) instead of “insufficient remaining capacity”.
• Add clarifying comments in BytesBuf::from_blocks / from_span_builders explaining why no overflow guard is required when aggregating exclusively owned Block/SpanBuilder capacity.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
crates/bytesbuf/src/buf.rs	Adds explanatory comments about why overflow checks aren’t needed when aggregating exclusively owned capacity sources.
crates/bytesbuf/src/buf_put.rs	Fixes put_bytes panic documentation to match the real panic condition (overflow).

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