fix(harness): assert cross-channel (yield vs auto-send) conformance equivalence [AGX1-373]

Rebased on the pyright-clean foundation. Includes @OverRide on _RecordingTracer.handle
and relative conformance imports so the whole-repo pyright (scripts/lint) passes.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: declan-scale