build: bump @nextcloud/sharing to 1.0.0-beta.1

The Vue 3 unified sharing dialog (@nextcloud/sharing/dialog) is consumed by
the files_sharing sidebar bridge built with build/frontend (Vue 3 / nc-vue 9).

Assisted-by: ClaudeCode:claude-opus-4-8
Signed-off-by: skjnldsv <skjnldsv@protonmail.com>

Author: skjnldsv