fix(config): restore current-task Motrix owners

[TATP-233]

Driving issue

Closes #2080

Delivered behavior

Restores six Motrix owner YAML files that were accidentally removed with the retired/shelved owner cleanup in 402aed69, but whose task identities remain active in main:

• APPO g1_motion_tracking
• FlashSAC g1_walk_flat
• PPO g1_motion_tracking
• PPO g1_walk_flat
• PPO go2_joystick_flat
• SAC g1_motion_tracking

Each restored file was compared byte-for-byte against 402aed69^; all six are exact historical copies. The already-restored/rewritten canonical owners (appo/go2_joystick_flat, flashsac/g1_motion_tracking, sac/g1_walk_flat) are unchanged.

The generated bilingual support matrix sections were refreshed, and the Go2 PPO Motrix grade assertion was restored to its historical generated semantics (Registered → Tested).

Scope / impact

• Motrix only; no MuJoCo owner values or training implementation changes.
• No retired task or task identity is reintroduced.
• No new public contract, backend capability, or production support claim is added.
• Does not affect macOS/Linux platform behavior beyond restoring the owner configs.
• Does not alter the three independently restored canonical Motrix owners.

Validation on final head (c23f576e)

make check
# Passed:
# - ruff format/check
# - mypy src/unilab: no issues
# - pyright: 0 errors
# - focused ruff test checks

make test-all
# Passed:
# - make check
# - pytest -m "not slow" --cov: 1843 passed, 22 skipped, 489 deselected
# - benchmark smoke: module-mode 34/34; script-mode 35/35

Focused checks also passed before commit:

uv run pytest tests/config tests/scripts/test_support_matrix.py --deselect tests/config/test_locomotion_params.py::test_ppo_g1_motion_tracking -q -m 'slow or not slow'
# 77 passed, 1 deselected

uv run pytest tests/tasks/test_go2_tensor_runtime.py tests/algos/test_appo_runner.py tests/scripts/test_train_script_configs.py tests/tasks/test_motion_term_parity.py tests/scripts/test_g1_flashsac_backend.py -q -m 'slow or not slow'
# 98 passed, 2 skipped

Known unrelated issue

tests/config/test_locomotion_params.py::test_ppo_g1_motion_tracking fails on main before this change (interactive.action_mode == "zero", expected "policy"). It is caused by X2 assertions being collapsed into the G1 test in da1d75f2, not by restoring these owners. This PR intentionally does not piggyback that unrelated fix.