Add new constructors and Default trait implementations to consolidate
RigState initialization patterns. This eliminates 195 lines of duplicated
struct literals across server and client.
New methods:
- RigState::new_uninitialized() - for client-side initialization
- RigState::new_with_metadata() - for server-side with config values
- RigState::from_snapshot() - convert RigSnapshot to full state
- Default for RigStatus - 2m calling frequency (144.3 MHz) in USB mode
- Default for RigControl - disabled with no active repeater settings
Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
Signed-off-by: Stanislaw Grams <stanislawgrams@gmail.com>