✨(backend) add documents/all endpoint with descendants

External dashboards need to find the latest updated documents across
the entire hierarchy. Currently this requires many API calls to
/documents/ and /documents/{id}/children for each level.
   
This endpoint allows retrieving all accessible documents in a single
request, enabling dashboards to efficiently display recently changed
documents regardless of their position in the hierarchy.
    
Signed-off-by: ChristopherSpelt <christopherspelt@icloud.com>

CHANGELOG.md

@@ -6,6 +6,10 @@ and this project adheres to
 
 ## [Unreleased]
 
+### Added
+
+- ✨(backend) add documents/all endpoint with descendants #1553
+
 ## [4.3.0] - 2026-01-05
 
 ### Added