refactor(core): extract RecordStore from interceptor

[mkilijanek]

Summary

Refactor record retention/spooling into dedicated core/record_store.py and integrate it from interceptor.

Why

• isolates complex record-buffer/spool logic from proxy flow
• improves maintainability and testability of storage behavior
• enables safer follow-up improvements (spool guards/rotation)

Notes

• this PR intentionally carries runtime refactor only
• upstream does not include full test suite from fork, so tests are excluded here

Validation

• python3 -m py_compile evilwaf.py core/*.py chemistry/*.py

Provenance

• cherry-picked (with conflict resolution) from fork commit b6654de

[mkilijanek]

Merge order note: please merge after #19.\n\nDepends on: #19