refactor(map): address Q10 decoding review feedback

[tubededentifrice]

Follow-up to #881 addressing the review feedback left just after it merged.

• use the DPS-native base64 str | None boundary for Q10 zone and virtual-wall blobs, keeping decoded bytes internal
• replace the compact calibration classification expression and magic numbers with a named enum and an explicit row-major classification pass
• expose Q10 grid decomposition as Q10MapPacket.layers
• move Q10 classifier/layer tests into test_b01_q10_map_parser.py

Validation:

• pre-commit run --show-diff-on-failure --color=always --all-files
• pytest -q (782 passed, 86 snapshots passed)