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.

CHANGELOG.md

@@ -7,6 +7,14 @@ release and covers the full history from the initial commit.
 
 ## [Unreleased]
 
+### Security
+
+- Private keys are no longer precomputed for every address in the UI. Address rows and the
+  address detail sheet carry only public data and derivation coordinates; the WIF is derived
+  when the user reveals it (after the password) and dropped when hidden, when the sheet closes
+  or when the wallet closes. Before, the WIF of every listed address sat in UI-bound strings for
+  the whole session.
+
 ### Fixed
 
 - The wallet now verifies the chain identity of a server right after connecting: the