Replace fragmented random key generation with a single 24-word BIP-39
mnemonic that deterministically derives all node keys: Ed25519 (DID),
secp256k1 (Nostr/Bitcoin), BIP-84 xprv (Bitcoin Core), and LND aezeed
entropy. New onboarding flow: seed generate → word verification → identity
naming. Restore path enabled via 24-word entry. Includes seed RPC handlers,
mock backend support, LND/Bitcoin Core wallet-from-seed integration, and
UI polish across settings and discover views.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
- Create mesh/session.rs: SessionManager for Double Ratchet state lifecycle
- Lazy-loads sessions from disk on first message
- Saves after every encrypt/decrypt (chain key advancement)
- Per-DID storage at {data_dir}/ratchet/{sha256(did)}.json
- Session info API for RPC status reporting
- Zeroize on drop for all key material
- Tests: store+load roundtrip, encrypt/decrypt through manager, session removal
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>