test(deploy): comprehensive deploy pipeline coverage (222 tests)

[doctor]

222 tests covering the full rfx deploy pipeline end-to-end.

Responding to the request to stress-test deployment in depth. Coverage includes:

1. deploy() — all source types (.py, directory, hf://), all robot configs (so101/go2/g1), all flags (port, rate_hz, warmup, device, verbose, mock)
2. _resolve_robot_config — every resolution path (explicit, YAML, auto-detect, fallback)
3. _create_robot — mock and real robot creation
4. _run_deploy_loop — all 3 branches (silent, verbose+timed, verbose+infinite) + error propagation
5. Session — lifecycle, context manager, threading, health checks, start/stop idempotency
6. observation.py — padding, truncation, frame stacking buffer, unpad (2D/3D)
7. MockBackend — spring-damper physics convergence, position clamping, partial env reset, reward/done
8. MockRobot — Robot protocol conformance, multi-env support
9. SimRobot — backend selection, config types (YAML/dict/RobotConfig), render/close safety
10. @rfx.policy — decorator discovery (with and without parens)
11. MotorCommands — joint name → tensor mapping, all 3 robot configs, error paths
12. load_policy — config/normalizer/robot_config loading paths
13. hub.py — _resolve_source, inspect_policy, push_policy
14. RobotConfig — YAML, dict, nested cameras/joints, search paths, RFX_CONFIG_DIR
15. All 3 builtin configs — deep validation (G1 29-DOF joint ordering, SO101 joint names, Go2 200Hz)
16. CLI bridge — all error paths (KeyboardInterrupt, ValueError, FileNotFoundError, generic)
17. Signal handling — SIGINT handler restoration
18. Real integration — deploy() with actual MockRobot + Session + torch tensors, no mocks