Root cause: board._sidebar_data tried int(gitea:owner:repo) → ValueError → lost context
Library, Trash, page editor pages showed empty workspace tree
Fix: board._sidebar_data now mirrors dashboard._sidebar_data logic:
- Detects gitea: prefixed cookie
- Preserves active_ws_name, workspace_key, gitea_workspace
- Loads local_ws_id for mirror workspace
- Tree stays visible on /library, /trash, page editor, etc.