fix(config): write only strict JSON configs; add a stored-config check

[georgevigelette]

Console firmware with the strict-config check (console-fw fix/jsmn-strict, CFW-12/CFW-15) stores a user config only when it is a strict JSON object that fits its page, and parses the stored config in jsmn strict mode at boot.

• MotionConfig.to_wire_bytes raises ValueError, naming the key path, for NaN or infinite values (json.dumps used to write NaN / Infinity, which the console now refuses), and for JSON longer than MOTION_CFG_JSON_MAX_LEN (2019 bytes: the 2036-byte page minus the 16-byte header and the NUL). json.dumps runs with allow_nan=False.
• strict_json_problem(text) explains why a config text would not pass: NaN / Infinity / -Infinity, out-of-range numbers, malformed JSON, a non-object root, or too long. Python's json.loads accepts NaN and Infinity, so it is not enough on its own.
• MotionConsole.write_config logs that the console refused the write and kept the stored config when the reply is OW_ERROR.
• scripts/check_console_config.py reads the raw stored config (read-only) and fails when it is not strict JSON or has no positive TEC_TRIP. Run it on each console, on its current firmware, before updating it to the strict firmware.

Tests: tests/test_motion_config_strict.py (no hardware). Software suite: no new failures.

Bench:

• strict firmware: the check passes on the stored config, fails (exit 1) on a config without TEC_TRIP, and passes again after restoring it;
• next firmware (5c0dc46): a config with EE_GAIN NaN was stored (RESP), and the check reported "non-JSON constant NaN" (exit 1); config restored.

Summary

Licensing layer

• Apache-2.0 extension (3D Slicer, wellness/veterinary module, partner SDK, language binding)
• AGPL-3.0 core (firmware, sensing/beamforming/reconstruction/signal-processing/calibration algorithms, hardware reference design)
• Docs / data / tooling only
• This PR moves a file between the AGPL core and the Apache layer — if checked, this is NOT an ordinary PR: it requires the license-manifest change process (and board approval for anything leaving the core). Link the approval.

Checklist

• Commits are signed off (DCO): git commit -s
• New files carry the correct SPDX-License-Identifier for their layer
• Tests and docs updated
• No incompatible third-party code introduced
• CI is green and CODEOWNERS review requested

Notes for reviewers