CVE-2026-62323: Cloudreve WOPI view sessions can write files and WOPI access token secret is ignored

Cloudreve WOPI access tokens are generated as <session-id>.<random-secret>, but the WOPI middleware validates only the session id prefix and never compares the supplied token to the stored token. In addition, a WOPI viewer session does not store or enforce the requested viewer action. A session created for a view or preview action can still call WOPI write routes if the underlying file is writable by the session user.