🐛(backend) preserve recording metadata when updating room access

Updating room access rewrote the entire metadata payload, removing information
about active recordings. This caused the frontend to lose track of ongoing
recordings and could trigger 409 errors when attempting to start a new
recording.

Consolidate the duplicated metadata update logic into
`RoomManagement.update_metadata()` and preserve merge behavior instead of
overwriting the full metadata object.

CHANGELOG.md

@@ -13,12 +13,6 @@ and this project adheres to
 - ✨(summary) report exception type in failure analytics
 - ✨(frontend) add configurable documentation menu item
 
-## Fixed
-
-- 🐛(transcription) fix silent bug in speaker assignment
-- 🐛(summary) extend tasks auto retry logic
-- 🐛(summary) properly detect when failure webhook should be sent
-
 ### Changed
 
 - ⬆️(frontend) upgrade @mediapipe/tasks-vision from 0.10.14 to 0.10.35
@@ -28,6 +22,13 @@ and this project adheres to
 - ⬆️(frontend) upgrade livekit-client from 2.19.2 to 2.20.0
 - ⚡️(frontend) limit unnecessary re-renders #1510
 
+## Fixed
+
+- 🐛(transcription) fix silent bug in speaker assignment
+- 🐛(summary) extend tasks auto retry logic
+- 🐛(summary) properly detect when failure webhook should be sent
+- 🐛(backend) preserve recording metadata when updating room access
+
 ## [1.24.0] - 2026-07-21
 
 ### Added