🐛(frontend) conditionally render AI button in toolbar

Added a feature flag check to ensure the AIGroupButton is only rendered
when AI_FEATURE_ENABLED is explicitly set to "true". This prevents the
AI button from appearing when the feature is not configured or disabled.

Fixes #782

Signed-off-by: Matthias <matthias@universum.com>

CHANGELOG.md

@@ -25,6 +25,7 @@ and this project adheres to
 
 ## Fixed
 
+- 🐛(frontend) conditionally render AI button only when feature is enabled #814
 - 🐛(backend) compute ancestor_links in get_abilities if needed #725
 - 🔒️(back) restrict access to document accesses #801