revert: remove public Harness Sidecar release artifacts

[zyn080302]

Summary

• Revert fix(test): support tomli on Python 3.10 #166, the Python 3.10 compatibility follow-up for the integration tests.
• • Revert feat(harness): add optional Sidecar integration release artifacts #165, including the optional integration distribution, SDK hook changes, and dual-wheel release workflow.
• • Restore the public SDK tree to its exact pre-feat(harness): add optional Sidecar integration release artifacts #165 state.

Reason

The delivery strategy changed: the public integration will be built separately and delivered from customer-controlled TOS through an explicit installer. VeADK will no longer resolve this integration from the public SDK extra.

Compatibility

• Keeps the SDK version at 0.8.2; no unrelated runtime behavior is changed.
• • Restores the release workflow to its original single-SDK-artifact behavior.
• • Removes the new integration publisher/token requirement from this repository.

Validation

• Final Git tree matches pre-feat(harness): add optional Sidecar integration release artifacts #165 commit a9508c3 exactly.
• • Toolkit CLI tests: 466 passed.
• • Diff-scoped pre-commit hooks passed.
• • Root SDK wheel and sdist built successfully and passed twine check.
• • Built SDK metadata contains no Harness Sidecar extra, integration dependency, or Sidecar module.