fix(downloads): confirm before clearing a link password; fix placeholder

Review follow-up on the share-link password UI:
- Removing a link's password makes it publicly watchable, a protection
  downgrade; gate it behind a danger-confirm like the neighbouring Revoke,
  spelling out that anyone with the URL can then watch without a password.
- When setting a first password the input reused the create-form "Password
  (optional)" placeholder, but it's required here (Save stays disabled until
  non-empty); use the "Set a password" wording instead.

frontend/src/components/ShareDialog.tsx

@@ -205,7 +205,7 @@ function LinkRow({ link, onChanged }: { link: ShareLink; onChanged: () => void }
               e.key === "Enter" && newPass.trim() && savePass.mutate(newPass.trim())
             }
             placeholder={t(
-              link.has_password ? "downloads.share.newPassword" : "downloads.share.password",
+              link.has_password ? "downloads.share.newPassword" : "downloads.share.setPassword",
             )}
             className="flex-1 min-w-0 bg-card border border-border rounded-md px-2 py-1 text-xs outline-none focus:border-accent"
           />
@@ -218,7 +218,17 @@ function LinkRow({ link, onChanged }: { link: ShareLink; onChanged: () => void }
           </button>
           {link.has_password && (
             <button
-              onClick={() => savePass.mutate("")}
+              onClick={async () => {
+                if (
+                  await confirm({
+                    title: t("downloads.share.removePassword"),
+                    message: t("downloads.share.removePasswordConfirm"),
+                    confirmLabel: t("downloads.share.removePassword"),
+                    danger: true,
+                  })
+                )
+                  savePass.mutate("");
+              }}
               disabled={savePass.isPending}
               className="px-2 py-1 rounded-md text-xs text-muted hover:text-red-400 transition"
             >

frontend/src/i18n/locales/en/downloads.json

@@ -123,7 +123,8 @@
     "changePassword": "Change password",
     "newPassword": "New password",
     "savePassword": "Save",
-    "removePassword": "Remove"
+    "removePassword": "Remove",
+    "removePasswordConfirm": "This makes the link public — anyone with the URL can watch it without a password."
   },
   "confirm": {
     "cancelTitle": "Cancel download?",

frontend/src/i18n/locales/hu/downloads.json

@@ -123,7 +123,8 @@
     "changePassword": "Jelszó módosítása",
     "newPassword": "Új jelszó",
     "savePassword": "Mentés",
-    "removePassword": "Törlés"
+    "removePassword": "Törlés",
+    "removePasswordConfirm": "Ezzel a link publikus lesz — jelszó nélkül bárki megnézheti, akinek megvan az URL."
   },
   "confirm": {
     "cancelTitle": "Megszakítod a letöltést?",