New fapp_router.rs module:
- FappAction enum (Ignore, Dropped, Forward, QueryResponse)
- Wire format: 1-byte tag (0x01-0x05) + CBOR body
- FappRouter with shared RoutingTable and TransportManager
- handle_incoming() decodes and dispatches FAPP frames
- process_slot_announce() with relay/flood logic
- process_slot_query() answers from local FappStore
- broadcast_announce() / send_query() for outbound floods
- drain_pending_sends() for async send integration
- 3 unit tests
Also fixed borrow checker issue in FappStore::store
Christian Nennemann
65ce5aec18