docs: v3.9.7 - OpusPlan workflow documentation

- CHANGELOG: Add 3.9.7 entry for CLAUDE.md Model Configuration
- Sync version numbers across cheatsheet and ultimate-guide
- OpusPlan hybrid workflow (Opus plan → Sonnet execute)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -6,6 +6,16 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## [Unreleased]
 
+## [3.9.7] - 2026-01-20
+
+### Changed
+
+- **CLAUDE.md: Model Configuration** — OpusPlan workflow recommendation (replaces thinking mode disable)
+  - Hybrid intelligence: Opus (planning) → Sonnet (execution)
+  - Task breakdown table: doc edits, version sync, restructuring, research, consistency checks
+  - Cost optimization: 10-20% Opus planning, 80-90% Sonnet execution
+  - Workflow: `/model opusplan` → `Shift+Tab × 2` (plan) → `Shift+Tab` (execute)
+
 ## [3.9.6] - 2026-01-20
 
 ### Added

guide/cheatsheet.md

@@ -6,7 +6,7 @@
 
 **Written with**: Claude (Anthropic)
 
-**Version**: 3.9.6 | **Last Updated**: January 2026
+**Version**: 3.9.7 | **Last Updated**: January 2026
 
 ---
 
@@ -411,4 +411,4 @@ where.exe claude; claude doctor; claude mcp list
 
 **Author**: Florian BRUNIAUX | [@Méthode Aristote](https://methode-aristote.fr) | Written with Claude
 
-*Last updated: January 2026 | Version 3.9.6*
+*Last updated: January 2026 | Version 3.9.7*

guide/ultimate-guide.md

@@ -10,7 +10,7 @@
 
 **Last updated**: January 2026
 
-**Version**: 3.9.6
+**Version**: 3.9.7
 
 ---
 
@@ -11151,4 +11151,4 @@ Thumbs.db
 
 **Contributions**: Issues and PRs welcome.
 
-**Last updated**: January 2026 | **Version**: 3.9.6
+**Last updated**: January 2026 | **Version**: 3.9.7