v2.6.0

## [2.6.0] — 2026-08-26 — Certification Consolidation + Engine Cleanup + v2.2 Promotion

### 🏆 Certified — 12 Families · 26 Model/Quant Combinations

Shimmy's certification pipeline has been **consolidated from the old 5-gate + CHAT regime into a clean 3-box regimen** (MATH + INFERENCE + DETERMINISM), matching the airframe 0.4.0 release. The regression-causing chat box is gone, replaced with deterministic inference verification.

**The 3-box certification regimen:**
1. **MATH** — GPU dequant audit, structural peel, plan-vs-peel reds, numerical self-consistency
2. **INFERENCE** — 5-prompt battery (factual / creative / arithmetic / kv_cache / dev_question) on real GPU
3. **DETERMINISM** — two identical runs must produce identical text

**26 certified model/quant combinations across 12 families** — up from 25 in v2.4.0. New: llama-3.1-8b, qwen2-7b, gemma-2-2b (plus re-certification of all prior models under the new regimen).

### Highlights

- **v2.2 release cleanup promoted to main** — Legacy engine code stripped (huggingface.rs, mlx.rs, universal.rs, rustchain_compat.rs removed — ~1,600 lines deleted). Feature flags cleaned. Shimmy is now a pure Airframe product.
- **CI simplified** — Removed huggingface/mlx/llama references from CI/CD. Faster, cleaner builds.
- **Certification alignment** — Shimmy's cert documentation, README, and supported-models tables now align with airframe's 3-box regimen and 26-model count.

### Removals

- **`engine/huggingface.rs`** (428 lines) — removed
- **`engine/mlx.rs`** (323 lines) — removed
- **`engine/universal.rs`** (573 lines) — removed
- **`src/rustchain_compat.rs`** (306 lines) — removed
- **`docs/rustchain-provider.md`** (40 lines) — removed
- All RustChain provider references scrubbed from docs, .gitignore, lib.rs

### Documentation

- **v2-roadmap.md** added (131 lines) — current roadmap and release planning
- Chinese user manuals updated
- Safetensors release status clarified

### Infrastructure

- **Beads issue tracking initialized** — `.beads/` Dolt-backed board for durable task tracking
- **Cargo.lock refreshed** for path-sourced airframe patch

### Commits
18 commits since v2.5.0 — see git log `v2.5.0..HEAD` for full list.