fix(record): harden L1 JSON parsing and embedding timeout

[YOMXXX]

Summary

• parse the first valid L1 scene payload instead of greedily matching from the first [ to the last ]
• tolerate non-JSON bracketed text and object-wrapped scene arrays with trailing text in model output
• pass embeddingTimeoutMs through L1 memory writes so slow CPU embedding providers can use the configured capture-path timeout
• add focused regression tests for L1 extraction parsing and vector dual-write embedding timeout propagation

Verification

• npm test
• npm run build

Fixes #110
Related: #181

[Maxwell-Code07]

@YOMXXX 4 PRs in one day tackling L1 extraction robustness — JSON parsing tolerance, dedup hardening, failure diagnostics persistence, and auto-retry. Great coverage! We'll review them one by one 🚀