keep the share tag out of the UI for everyone except admins

The tag has to live in the item's real Tags for Jellyfin's tag policy to confine
the guest, so normal users were seeing a "sharelinks-<guid>" chip on any shared
title and an entry for it in the library tag filter. Admins still see them; for
everyone else the chip is taken back out of the tag row, along with the ", "
Jellyfin puts between chips, and the whole row is hidden when the share tag was
the only one. The tag filter entry gets hidden too.

Only tags matching sharelinks- plus 32 hex are touched, so a real tag that happens
to start with "sharelinks" is left alone. Guests benefit as well, since they were
seeing the tag on the title they were sent.

Worth being clear about the limit: this is the web UI. The tag is still in the API
response, so anyone reading the raw API can see it.

Jellyfin.Plugin.ShareLinks/Web/sharelinks.js

@@ -21,6 +21,8 @@
     var menuTriggerSelector = '[data-action="menu"], .btnMoreCommands, .btnCardOptions, .cardOverlayButton';
     var itemTypeCache = {};
     var itemTypeInFlight = {};
+    var shareTagPattern = /^sharelinks-[0-9a-f]{32}$/i;
+    var tagHiddenAttr = 'data-sharelinks-tag-hidden';
     var historyPatched = false;
     var itemMenuActionIds = [
         'resume', 'playallfromhere', 'queue', 'queuenext', 'shuffle', 'instantmix',
@@ -194,6 +196,7 @@
     async function refresh() {
         rememberAllowedItemFromRoute();
         await applyGuestLockdown();
+        await hideShareTagsFromNonAdmins();
         await scanForMoreMenuActions();
     }
 
@@ -589,6 +592,77 @@
             });
     }
 
+    /**
+     * The share tag has to sit in the item's real Tags for Jellyfin's own tag policy
+     * to confine the guest, which means every user would otherwise see a
+     * "sharelinks-..." chip on the title and an entry in the library's tag filter.
+     * Administrators keep seeing them; for everyone else they are taken back out of
+     * the DOM. This is the web UI only - the tag is still in the API payload.
+     */
+    async function hideShareTagsFromNonAdmins() {
+        var user = await getCurrentUser();
+        if (!user || isAdministrator(user)) {
+            return;
+        }
+
+        stripShareTagChips();
+        hideShareTagFilters();
+    }
+
+    function stripShareTagChips() {
+        Array.prototype.forEach.call(document.querySelectorAll('.itemTags'), function (container) {
+            var removed = 0;
+            Array.prototype.forEach.call(container.querySelectorAll('a'), function (chip) {
+                if (!shareTagPattern.test(normalizeText(chip.textContent))) {
+                    return;
+                }
+
+                removeChipSeparator(chip);
+                chip.remove();
+                removed += 1;
+            });
+
+            if (removed > 0 && !container.querySelector('a')) {
+                // Nothing but the "Tags:" prefix would be left over.
+                container.textContent = '';
+                container.classList.add('hide');
+            }
+        });
+    }
+
+    /** Drops the ", " text node Jellyfin puts between two tag chips. */
+    function removeChipSeparator(chip) {
+        var separator = /^\s*,\s*$/;
+        var next = chip.nextSibling;
+        if (next && next.nodeType === 3 && separator.test(next.nodeValue)) {
+            next.parentNode.removeChild(next);
+            return;
+        }
+
+        var previous = chip.previousSibling;
+        if (previous && previous.nodeType === 3 && separator.test(previous.nodeValue)) {
+            previous.parentNode.removeChild(previous);
+        }
+    }
+
+    function hideShareTagFilters() {
+        Array.prototype.forEach.call(document.querySelectorAll('.chkTagFilter'), function (input) {
+            if (input.getAttribute(tagHiddenAttr) === '1') {
+                return;
+            }
+
+            if (!shareTagPattern.test(String(input.getAttribute('data-filter') || ''))) {
+                return;
+            }
+
+            input.setAttribute(tagHiddenAttr, '1');
+            var row = input.closest('label') || input.parentElement;
+            if (row) {
+                row.style.setProperty('display', 'none', 'important');
+            }
+        });
+    }
+
     function isCopyStreamUrlLabel(label) {
         var value = normalizeText(label).toLowerCase();
         if (!value) {