Missing functionality

The old Godot daccord client's space context menu lists Leave & Delete Data directly next to Leave Server. In the new Flutter client this destructive variant exists but is poorly discoverable — it lives only in Privacy & Data settings (_leaveAndDelete() calling client.members.leaveMe(space.id, deleteData: true) in lib/features/settings/views/privacy_settings_page.dart:94).

What's needed

• Surface a "Leave & delete data" action in the space context menu (_serverActionTiles in lib/features/spaces/views/accord_home_rail.dart), next to the existing non-destructive "Leave server".
• Keep a clear confirmation dialog given the destructive deleteData: true behaviour.
• Apply the same owner guard as plain Leave (owner must transfer ownership first).

Found while auditing the old client's space menu for feature parity.

Migrated from DaccordProject/daccord-app#77