Extract duplicate b2s/s2b functions from proxy/utils.go into
internal/utils/bytes.go. These are zero-allocation unsafe conversions
for byte slice <-> string conversion.
- Create utils.B2s() and utils.S2b() as unified implementations
- Update proxy/utils.go to call utils functions
- Add safety documentation about shared memory warning
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
