release: v3.27.6 - Sonnet 4.6 default + 200K vs 1M context guide

- Pricing table: Sonnet 4.6 now default (Feb 2026)
- New section: 200K vs 1M context decision guide (MRCR bench, cost table, use cases)
- threat-db.yaml v2.1.0: CVE-2026-23744, Slopsquatting T009, OWASP Agentic AI Top 10

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

README.md

@@ -6,7 +6,7 @@
 
 <p align="center">
   <a href="https://github.com/FlorianBruniaux/claude-code-ultimate-guide/stargazers"><img src="https://img.shields.io/github/stars/FlorianBruniaux/claude-code-ultimate-guide?style=for-the-badge" alt="Stars"/></a>
-  <a href="./CHANGELOG.md"><img src="https://img.shields.io/badge/Updated-Feb_17,_2026_·_v3.27.5-brightgreen?style=for-the-badge" alt="Last Update"/></a>
+  <a href="./CHANGELOG.md"><img src="https://img.shields.io/badge/Updated-Feb_18,_2026_·_v3.27.6-brightgreen?style=for-the-badge" alt="Last Update"/></a>
   <a href="./quiz/"><img src="https://img.shields.io/badge/Quiz-274_questions-orange?style=for-the-badge" alt="Quiz"/></a>
   <a href="./examples/"><img src="https://img.shields.io/badge/Templates-116-green?style=for-the-badge" alt="Templates"/></a>
   <a href="./guide/security-hardening.md"><img src="https://img.shields.io/badge/🛡️_Threat_DB-18_CVEs_·_341_malicious_skills-red?style=for-the-badge" alt="Threat Database"/></a>
@@ -757,7 +757,7 @@ See [CONTRIBUTING.md](./CONTRIBUTING.md) for guidelines.
 
 ---
 
-*Version 3.27.5 | Updated daily · Feb 17, 2026 | Crafted with Claude*
+*Version 3.27.6 | Updated daily · Feb 18, 2026 | Crafted with Claude*
 
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