Add 7 new modules with all core data types for the mesh routing protocol:
- tree.rs: ParentDeclaration, TreeCoordinate, TreeState
- bloom.rs: BloomFilter (4KB/7 hash), BloomState with debouncing
- transport.rs: TransportId, LinkId, Link, Transport trait, LinkStats
- protocol.rs: Auth messages, TreeAnnounce, FilterAnnounce, LookupRequest/Response, SessionSetup, DataPacket
- cache.rs: CoordCache, RouteCache with LRU eviction and TTL expiry
- peer.rs: Peer lifecycle states, filter tracking, UpstreamPeer
- node.rs: Node container with resource limits
All entities have constructors, error types, and comprehensive tests (161 total).
Stub methods with todo!() for behavior to be implemented later.
No state machine logic, protocol handlers, or async code yet.
Implements FIPS Identity System (Section 1 of design doc):
- NodeId: 32-byte SHA-256 hash of npub, with Ord for root election
- FipsAddress: 128-bit IPv6-compatible address (0xfd prefix)
- Identity: keypair holder with sign/verify methods
- AuthChallenge/AuthResponse: challenge-response authentication
All 11 tests passing.