v0.9 — Stable scaling & threshold extraction release

This release marks the first stable implementation of surface-code scaling and logical error rate (LER) threshold extraction using MWPM decoding.

Highlights

• Deterministic surface-code simulations for distances d = 3, 5, 7
• Stable logical error rate (LER) estimation with confidence intervals
• Reproducible results via fixed RNG seeds
• Batched trial execution with live progress logging
• Non-monotonic LER detection warning (finite-trial variance)
• Automatic CSV export for threshold analysis

Verified Capabilities

• Reliable large-scale runs (≥2000 trials)
• Consistent cross-run reproducibility
• No hang at higher distances (d=7 stress-tested)

This release establishes a stable foundation for upcoming hybrid CV + discrete QEC development in v1.0.