EEPROM verifier tests

Live under crates/ethercat-esi-verify/tests/.

Test Case: Verifier passes on matching ESI + SII pair TEST_0460
status: open
verifies: REQ_0560

Use the captured pair from crates/ethercat-eeprom-dump/dumps/EL3001/ (ESI XML + matching SII .bin), call verify(xml, sii), assert Ok(VerifyReport { matched: true, .. }).
Test Case: Verifier reports the differing field TEST_0461
status: open
verifies: REQ_0561

Synthetic mismatched pair: parse a real ESI but flip one bit in a captured SII to alter the revision field. The returned VerifyReport shall contain at least one Difference entry whose field is exactly "Identity.revision" and whose esi / sii values match the originals.
Test Case: Verifier reuses ethercat-esi parser TEST_0462
status: open
verifies: REQ_0562

White-box: cargo tree -p ethercat-esi-verify lists ethercat-esi as a direct dependency and does not list ethercrab anywhere in the graph (re-affirming Backend is the sole ethercr... (TEST_0423) from the verifier side).
Test Case: Verifier exit codes follow the documented matrix TEST_0463
status: open
verifies: REQ_0563

Spawn the verifier binary three times: matching pair (expect exit 0), mismatched pair (expect 1), unreadable SII path (expect 2). Asserted via Command::status().code().