Public API enhancements

[brothercorvo]

2. Core Object

Implement:

struct Node - internal runtime - command channel - event broadcast
channel - state tracking

Public API:

• new() -> Node
• start(config: NodeConfig)
• stop()
• restart(config: NodeConfig)
• get_status() -> NodeStatus
• send(destination, data, options) -> SendReceipt
• broadcast(data, options) -> SendReceipt
• set_log_level(level)
• subscribe_events() -> EventSubscription

3. Event System

NodeEvent union:

• StatusChanged
• PeerChanged
• PacketReceived
• PacketSent
• Log
• Error

EventSubscription:

• next(timeout_ms) -> NodeEvent?
• close()

Ensure: - Thread safe - No panics across FFI boundary - Structured error
types

4. Error Types

NodeError enum:

• InvalidConfig
• IoError
• NetworkError
• ReticulumError
• AlreadyRunning
• NotRunning
• Timeout
• InternalError