fix: recover interrupted sideload transfers

[zakoverflow]

Summary

• Clear stale card.binary receive state before sideload setup.
• Mirror note-c: retry only a {bad-bin} validation failure, up to three complete attempts.
• Wait one second between those attempts to accommodate observed Notecard-side timing races.
• Add mocked regression coverage for reset, successful retry, retry exhaustion, and non-{bad-bin} terminal failures.

Testing

• go test ./... -count=10
• go vet ./...
• go build ./notecard

No Notecard hardware was attached; transfer behavior is covered by mocked transport tests.