Test clear4 signed-context routing when only one side supplies context #2940

test/concrete/raindex/RaindexV6.clear.signedContextRouting.t.sol (added by #2920) pins clear4's per-order routing only when both sides supply signed context: own-context routing, swapped contexts revert, swapped domains revert.

Not covered: one side supplies signed context and the other supplies an empty array.

• alice non-empty, bob empty: alice's eval sees alice's signer/domain/content; bob's eval sees zero signers and no signed-data columns.
• alice empty, bob non-empty: the mirror.

Assert from inside each order's expression (signer count, signer, domain, content rows), as the existing routing tests do, so a routing that leaks one side's context into the other side's empty slot, or drops it, fails.