v0.7.0-rc.55

Highlights

• Added Config::onchain_wallet_accounts for loading derived account registrations during node build, plus runtime account removal that retains account-specific wallet state.
• Added indexed and ranged address lookup APIs for derived accounts.
• Added configurable Electrum full-scan batch size and stop gap for additional on-chain wallets, including recovery of externally issued xpub addresses.
• Updated Swift, Kotlin, Python, and native bindings for 0.7.0-rc.55.