fix: isolate Echidna parser state between parses

[arunimshukla]

Summary

• replace module-global Echidna parser state with state scoped to each FuzzingResults instance
• prevent optimisation metadata, trace flags, timestamps, and previous lines leaking between independent processLogs calls
• add a regression test that reproduces the cross-parse contamination

Why

processLogs creates a fresh result object for every parse, but the Echidna parser previously kept mutable state at module scope. A log ending after an optimisation result could therefore attach that result and its max value to the next unrelated log parsed by the same process.

Validation

• npm test -- --runInBand (329 tests passed)
• npm run build