v0.3.0 — Smarter Detection: Configurable Drift & Anomaly Scoring

v0.3.0 - Improved drift/anomaly detection, configurable parameters

Highlights:
- Anomaly detection: 20% → 80% detection rate
- Drift detection: 0% → 60% with realistic form revisions
- Scoring rebalanced: 60% spatial + 40% name
- All parameters configurable via field_memory.yaml
- FieldMemoryConfig class + TemplateMemory.from_config()
- STRESS_TEST_REPORT.md (90 complex PDFs, real Textract)
- 158 unit tests passing