fix(app): derive an address private key only when revealed

Address rows and the address detail sheet no longer carry the WIF of
every listed address for the whole session. The key is derived after the
password gate and dropped when hidden, when the sheet closes or when the
wallet closes. See ADR 0037.

docs/adr/README.md

@@ -10,6 +10,7 @@ One ADR per feature or significant design decision. Format: `template.md`. Workf
 | 0004 | [Centralize all chain constants in a network profile](0004-centralized-network-profile.md) | Chain | Accepted |
 | 0005 | [Use NBitcoin for protocol primitives, hand-write only the rest](0005-nbitcoin-for-protocol-primitives.md) | Crypto | Accepted |
 | 0006 | [Anchor headers to hardcoded checkpoints and skip PoW validation](0006-spv-checkpoint-anchoring-without-pow.md) | SPV | Accepted |
+| 0037 | [Derive an address private key only when it is revealed](0037-derive-address-private-keys-on-reveal.md) | Security | Accepted |
 | 0007 | [Verify a Merkle proof for every confirmed transaction](0007-mandatory-merkle-verification.md) | SPV | Accepted |
 | 0008 | [Progressive verification: show early, spend only after proof](0008-progressive-verification-sync.md) | SPV | Accepted |
 | 0009 | [Hand-written Electrum JSON-RPC client with pipelining and an in-flight cap](0009-custom-electrum-client.md) | Network | Accepted |