Share dialog says 'Only you.' under 'Who has access' while the item has public links #407

Where: web/src/components/ShareDialog.vue:257-262. The v-else on the member list shows share.onlyYou.

What happens: Open "Share …" on a file that has an active public link and no member share. The dialog says "Wer hat Zugriff: Nur du." (en: "Who has access: Only you.") and lists, directly below, the public link that anyone can open. #382 fixed this in the details drawer, which lists active links and says "Only you." only when there is neither (DetailsDrawer.vue:205-225). The share dialog still contradicts itself.

Expected: "Only you." appears only when there is neither a member share nor an active public link (not expired, downloads left), as in the drawer. With links but no members, a sentence says so, for example:

• en: "No members. Anyone with a public link below can open it."
• de-du and de-sie: "Keine Mitglieder. Wer einen der öffentlichen Links unten hat, kann es öffnen."

Fix: Compute the active links in ShareDialog. LinkManager already loads them, so it can emit them, or the dialog can share the query. Choose the sentence from both lists. Add the i18n key in all three locales.

Test (Playwright, e2e/shares.spec.ts): Create a public link for a file through the API and open "Share …". "Only you." is absent and the new sentence is shown. Revoke the link: "Only you." shows. Fails today.

Found by the automatic review round (claude-opus-5-5, b739414); per CLAUDE.md the fix starts with a failing behaviour test.