* chore: refactor codebase before meshcore release
* data: run black
* fix: resolve SonarCloud S1244/S5796 reliability issues in test files
Replace floating-point equality comparisons with pytest.approx() to
satisfy S1244, and replace the `is` identity operator with id()-based
comparison to satisfy S5796.
* fix: remove duplicate encrypted_flag assignment in store_packet_dict
The encrypted_flag was computed identically on lines 307 and 345 with no
mutation of `encrypted` between them. Remove the dead second assignment.
* Floor override frequencies to MHz integers
* Handle stub protobuf nodeinfo dictionaries
* Handle zero override frequency defaults
* Add defensive serialization coverage
* Stabilize nodeinfo user role normalization test
l5y