chore: release v0.1.1 (#798)

Prepares the v0.1.1 release.

## Changes
- Bumps workspace version: 0.1.0 → 0.1.1
- Moves [Unreleased] CHANGELOG entries to [v0.1.1] with today's date
(2026-02-26)

## What's in v0.1.1

### SRP Microcrates
- `bitnet-device-probe`, `bitnet-logits`, `bitnet-generation`,
`bitnet-engine-core`, `bitnet-gguf` extracted and wired into CI

### Backend & Runtime
- Backend capability detection and registry (`BackendStartupSummary`):
startup logs `requested=X detected=[…] selected=Y`
- BDD grid runner (`xtask grid-check`) added to CI Core workflow

### Test Quality
- 50 crates with proptest coverage (up from ~20)
- 15 fuzz targets (up from 11); nightly fuzz CI with corpus caching
- GPU smoke lane with weekly schedule and receipt upload
- CPU golden-path E2E tests (reproducibility + pinned-output regression
guard)
- 30 tests unblocked: 110 → 78 ignored tests
- ~37 snapshot test files, 200+ insta assertions

### Kernel & Quantization
- TL1 and TL2 kernel correctness fixes (dequantize+matmul pipeline)
- QK256 (GGML I2_S) pure-Rust support with dual flavor detection
- AVX2 QK256 dequantization foundation (~1.2× uplift)

### Security & Reliability
- Model path validation: symlink traversal prevention, allowlist
hardening
- Env-var race conditions eliminated workspace-wide (temp_env + serial)
- Security audit: bytes 1.11.1, time 0.3.47

### Documentation & DX
- README modernized (badges, feature flags table, architecture diagram)
- First-inference tutorial, docs archive cleanup (136 stale files moved)
- Probot settings, markdownlint npm resilience

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: EffortlessSteven

CHANGELOG.md

@@ -4,6 +4,8 @@ All notable changes to bitnet-rs will be documented in this file.
 
 ## [Unreleased]
 
+## [v0.1.1] - 2026-02-26
+
 ### Security
 - Restrict model loading to configured directories via `BITNET_ALLOWED_MODEL_DIRECTORIES` (#753)
 - Harden model path validation: prevent symlink traversal and empty-string allowlist bypass (#756)