Ecash gets its own BIP-39 mnemonic derived from the node master seed:
still covered by the node's recovery phrase, but portable into any NUT-13
wallet without exposing the master seed — so 'back up my ecash' is not the
same action as 'expose the key to everything'.
Surfaced exactly like the Lightning seed: the shared SeedRevealPanel, on
the app detail page and in Settings → Backup, behind the same
verify_reveal_auth password re-entry. Standard BIP-39, so the SeedQR tab
works (no aezeed flag).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Scoped from the framework-pt keyset incident: adopt the `cashu` crate
(MIT, the crate CDK is built on) for the token codec, keyset ids, crypto,
DLEQ and NUT-13, while keeping ecash.rs's on-disk contract, MintClient's
Tor seam and error table, and our multi-mint routing. Records why the
full cdk WalletDatabase shim is the wrong trade over live funds, and how
ecash backup can derive from the node's existing seed.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
