fix: force bash shell for cross-platform compatibility

- Add explicit shell: bash to resolve PowerShell syntax errors
- Ensure consistent bash commands across Windows/Linux/macOS
- Fix Poetry version check and dependency listing

🤖 Generated with [Claude Code](https://claude.ai/code)

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

Author: lluc

.github/workflows/build-executables.yml

@@ -141,6 +141,7 @@ jobs:
           echo "📦 Using pip directly"
           python -m pip list | grep -E "(customtkinter|pystray|[Pp]illow|pyinstaller)" || true
         fi
+      shell: bash
 
     # 10. Build de l'exécutable
     - name: 🔨 Build Executable
@@ -153,6 +154,7 @@ jobs:
           echo "⚠️ Building with Python directly"
           ${{ matrix.build_command }}
         fi
+      shell: bash
 
     # 11. Vérification du build
     - name: ✅ Verify Build Output