RULES.md: state every action that asks for the password (closes #756)

Replace the Secrets & Storage line "Password only required for signing
operations" with the wording sneak approved: the password is required for
signing, deleting a wallet, and showing a recovery phrase or private key.

Model: opus-5-5

RULES.md

@@ -99,7 +99,8 @@ contradicts either, the originals govern.
 
 - [ ] Public data (xpubs, addresses, balances) stored unencrypted
 - [ ] Private data (recovery phrases, private keys) encrypted at rest
-- [ ] Password only required for signing operations
+- [ ] Password required for signing, deleting a wallet, and showing a recovery
+      phrase or private key
 - [ ] No secrets in `.env`, credentials, or API keys committed to repo
 - [ ] `git add -A` / `git add .` never used