docs: wire OpenSSF Best Practices badge (project 12993)

Adds the bestpractices.dev/projects/12993 badge to the README header
alongside the existing OpenSSF Scorecard + SLSA Level 3 badges.
Project is registered; questionnaire pending. The badge image will
auto-update from "in progress" to "passing" once the criteria reach
the 75% threshold. CHANGELOG #218 note refreshed accordingly.

---
THE ARCHITECT ᛫ Sebastien Rousseau ᛫ https://sebastienrousseau.com
THE ENGINE ᛞ EUXIS ᛫ Enterprise Unified Execution Intelligence System ᛫ https://euxis.co

Assisted-by: Claude:claude-opus-4-7

Author: sebastienrousseau

CHANGELOG.md

@@ -86,9 +86,10 @@ v0.0.10.
 
 ### Remaining open alerts (require GitHub UI / external action)
 
-- **CII Best Practices badge** (Scorecard #218) — register at
-  bestpractices.coreinfrastructure.org and complete the
-  questionnaire. Not branch-fixable.
+- **CII Best Practices badge** (Scorecard #218) — project
+  registered at bestpractices.dev/projects/12993 and badge wired
+  into README. Questionnaire still in progress; Scorecard credit
+  arrives once the badge reaches `passing` (≥ 75% met).
 - **Code Review 2-reviewer rule** (Scorecard #216) — requires
   branch-protection config in repo Settings → Branches.
   Not branch-fixable.

README.md

@@ -22,6 +22,7 @@
   <a href="https://codecov.io/gh/sebastienrousseau/hsh"><img src="https://img.shields.io/codecov/c/github/sebastienrousseau/hsh?style=for-the-badge&logo=codecov" alt="Coverage" /></a>
   <a href="https://lib.rs/crates/hsh"><img src="https://img.shields.io/badge/lib.rs-hsh-orange.svg?style=for-the-badge" alt="lib.rs" /></a>
   <a href="https://securityscorecards.dev/viewer/?uri=github.com/sebastienrousseau/hsh"><img src="https://img.shields.io/ossf-scorecard/github.com/sebastienrousseau/hsh?style=for-the-badge&label=OpenSSF" alt="OpenSSF Scorecard" /></a>
+  <a href="https://www.bestpractices.dev/projects/12993"><img src="https://www.bestpractices.dev/projects/12993/badge" alt="OpenSSF Best Practices" /></a>
   <a href="https://slsa.dev/spec/v1.0/levels"><img src="https://img.shields.io/badge/SLSA-Level%203-brightgreen?style=for-the-badge" alt="SLSA Level 3" /></a>
 </p>