chore: remove redundant sign status & bump checkpoint version

[ChaoticTempest]

sign status is redundant inside BidirectionalTx since it's already in BacklogEntry. So removing it and bumping checkpoint version (which is needed to remove some stale requests).

[Copilot]

Pull request overview

This PR simplifies bidirectional transaction tracking by removing the redundant SignStatus from BidirectionalTx (status already lives on BacklogEntry) and bumps the persisted checkpoint key version to invalidate older checkpoint data.

Changes:

• Remove status: SignStatus from BidirectionalTx and update construction sites accordingly.
• Update stream/backlog logic and tests to rely on BacklogEntry for status.
• Bump Redis checkpoint key version from v2 to v3 to drop stale persisted requests.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
integration-tests/tests/cases/ethereum_stream.rs	Updates integration test BidirectionalTx initialization to match the new struct shape.
chain-signatures/node/src/stream/ops.rs	Removes redundant status plumbing when creating/completing bidirectional transactions.
chain-signatures/node/src/storage/checkpoint_storage.rs	Bumps checkpoint storage key version to v3 to invalidate old persisted checkpoints.
chain-signatures/node/src/sign_bidirectional.rs	Removes status from BidirectionalTx definition.
chain-signatures/node/src/backlog/mod.rs	Updates backlog tests/helpers to pass status independently of the tx struct.

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[Copilot]

create_execution_entry constructs a BacklogEntry with an execution tx (Some(tx)), but it accepts an arbitrary status. That makes it easy for tests to create impossible states (e.g., AwaitingResponse with an execution tx), which can mask bugs. Consider making this helper always use SignStatus::PendingExecution (or renaming it to reflect that it can create inconsistent combinations / adding a debug assert that status != AwaitingResponse when execution is Some).

Suggested change

	) -> BacklogEntry {
	) -> BacklogEntry {
	debug_assert!(
	!matches!(status, SignStatus::AwaitingResponse),
	"create_execution_entry cannot create an execution entry with AwaitingResponse status"
	);

[Copilot]

These entries include an execution tx via create_execution_entry(..., Some(tx)), so using SignStatus::AwaitingResponse here represents a state that should not happen in production (execution is only set after advancing, which sets status to PendingExecution). Updating these to PendingExecution (and adjusting the helper accordingly) will make the checkpoint equality test reflect real backlog states.

[Copilot]

This test later calls take_execution_tx() and expects a "pending execution entry", but the entry is created with SignStatus::AwaitingResponse. To keep the serialized checkpoint representative of real data, set the status to PendingExecution (or use a helper that always sets that status when execution is present).