This pull request introduces a new system for communicating which LoRa modem presets are legal in each region from the firmware to clients, allowing client UIs to prevent users from selecting invalid region and preset combinations. The changes add new protobuf messages and options to efficiently encode this mapping, ensuring the data fits within protocol size limits.

LoRa region and preset compatibility mapping:

• Added a new LoRaRegionPresetMap message to FromRadio, sent during the configuration handshake, which describes the valid modem presets for each LoRa region. This enables clients to enforce legal region+preset selections and warn users about licensed-only regions.
• Introduced supporting messages: LoRaPresetGroup (describes a set of legal presets, the default preset, and licensing status for regions), and LoRaRegionPresets (associates a region with a preset group).
• Documented the structure and rationale for these new messages, including how grouping regions by shared preset lists keeps the mapping compact and fits protocol constraints.

Protocol size and option constraints:

• Updated mesh.options to define max_count and int_size for the new fields, ensuring the region-preset map remains within the protocol's maximum message size.