fix: outgoing body capture stream preservation

[georgidhristov]

Fixes #114

Summary

Fixes outgoing HTTP body capture so DebugProbe limits how much body content is read without consuming the response stream for the application.

Changes

• Read only up to MaxBodyCaptureSizeBytes + 1 when capturing outgoing bodies
• Mark captured bodies as [truncated] when they exceed the configured limit
• Preserve outgoing response behavior by replaying captured bytes back to the caller
• Respect the response body charset during capture
• Add regression tests for streamed response preservation and charset handling