Gate OVRTX and OVStage compatibility

[nvsekkin]

Summary

• Reject unsupported OVRTX/OVStage native package pairs before renderer construction.
• Add focused compatibility coverage for the 0.4/0.1 and 0.5/0.2 release lines.
• Add a maintainer-controlled ci:run-ovstage PR lane and paired wheelhouse provenance checks.

Validation

• 97 passed across OVRTX compatibility, renderer-contract, and USD tests.
• uv run isaaclab -f passed against PR Add optional support for ovrtx-0.5 isaac-sim/IsaacLab#7351 as the changelog base.
• Exact OVRTX 0.5.0.0 + OVStage 0.2.0.370625 prevented the native population crash.
• Legacy Cartpole static rendering passed; OVStage rendered successfully and exposed only a 2.00% golden difference at a 1.50% threshold.

Dependency note

The public pins remain unchanged in this follow-up. ovphysx==0.5.10 requires ovstage==0.1.1.355824, so the aggregate ov extra cannot move to OVStage 0.2 until a compatible OVPhysX build is available or the extras are explicitly separated.