Examples have no systematic test coverage; GPU example tests must be hand-registered

Problem

There is no systematic way to test an example, and no convention for where an example test belongs. Examples are separate uv projects, so nothing in a normal build imports or runs them — an example can drift away from the library beside it and only fail when a user runs it. That is not hypothetical: mcap_record_replay and deviceio_live_view shipped pinned to isaacteleop==1.3.9rc1 and every script died on ImportError: cannot import name 'BodyJointIndex' before it started.

Survey of examples/ (15 examples)

Orphaned tests. examples/oxr/python/ holds nine test_*.py; only three are listed in CXR_PYTHON_GPU_TESTS. These six are copied into the test container by Dockerfile.test and then never invoked:

• test_controller_tracker.py
• test_full_body_tracker.py
• test_hand_inactive_on_plugin_stop.py
• test_oak_camera.py
• test_session_sharing.py
• test_synthetic_hands.py

Why it keeps happening

1. GPU/runtime tests are hand-registered in a bash array in scripts/run_tests_with_cloudxr.sh. Nothing discovers them, so adding a file next to nine others silently does nothing — which is how six accumulated.
2. The container only sees one example. deps/cloudxr/Dockerfile.test hardcodes COPY examples/oxr/python/ /app/tests/, so no other example's tests can reach the CloudXR runtime without editing the Dockerfile.
3. No home for non-GPU example tests. camera_viz puts them in tests/ with its own pyproject; oxr puts them beside the scripts. Neither is documented as the convention.

What would fix it

• Discover GPU example tests instead of listing them, and generalise the COPY so any example can contribute tests to the CloudXR container.
• Pick one convention for headless example tests (ctest entry + uv run --no-project, isaacteleop from the build tree on PYTHONPATH) and document it.
• Decide the six orphans' fate: wire them up or delete them.
• Give the five unbuilt examples at least an import/lint check so they cannot silently rot.

Starting point for the headless half: PR #879 discussion.

Start with scripts/run_tests_with_cloudxr.sh, deps/cloudxr/Dockerfile.test, the CMake example test entries, and the PR #879 discussion. Trace how CXR_PYTHON_GPU_TESTS and the hardcoded examples/oxr/python/ copy work, then compare camera_viz and oxr conventions. Done means example tests are discoverable or explicitly handled, unbuilt examples receive checks, and the convention is documented.