Refocus Electrum v1 old-mnemonic regression on dogecoin_seed_from_electrum_v1_mnemonic

[Copilot]

• Review current Electrum v1 test changes and identify non-function-based assertion logic
• Confirm desired behavior should be asserted from dogecoin_seed_from_electrum_v1_mnemonic output
• Update test to validate expected vector strictly via dogecoin_seed_from_electrum_v1_mnemonic
• Keep changes minimal and avoid altering unrelated Electrum v1 derivation behavior
• Rebuild and run targeted tests
• Run code review and security scan, then finalize

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