test: accept resolved Windows handoff adapters

[PracticalSwan]

Summary

• make the execute/watch/loop handoff smoke accept a resolved Windows .cmd adapter path instead of requiring the literal bare command name
• keep the same adapter identity assertion on non-Windows platforms

Why

On Windows, normal command resolution can return an absolute *.cmd shim for tools such as OpenCode. The release smoke treated that valid resolved adapter as a failure even though the handoff execution path was correct.

Verification

• clean branch based on upstream main
• node scripts/execute-handoff-smoke.mjs — passed
• git diff --check — passed