fix(ui): improve user filter dropdown when no remote search is configured (#40296)

On the dashboard issue and pull request pages, author and assignee
filters only accept direct username input since candidate lists across
all accessible repositories cannot be pre-fetched. However, the dropdown
inherited several confusing artifacts from the repository-level user
search:

- Displayed a misleading "Shows a maximum of 30 users" tooltip even
though no remote user list was fetched.
- Used "Search users" as placeholder rather than indicating direct
username input.
- Pressing Enter in the input had no effect, requiring mouse selection.
- Any active username filter was not reflected in the dropdown menu on
open.

This change:
- Only renders the 30-user tooltip when a remote search URL is provided.
- Uses "Filter by username…" as placeholder when no remote search URL
exists.
- Applies the filter on Enter keypress.
- Ensures the active username is displayed and selected when opening the
menu.

Fixes: https://github.com/go-gitea/gitea/issues/40275
Fixes: https://github.com/go-gitea/gitea/issues/33426

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

options/locale/locale_en-US.json

@@ -1464,6 +1464,7 @@
   "repo.issues.filter_assignee_any_assignee": "Assigned to anybody",
   "repo.issues.filter_poster": "Author",
   "repo.issues.filter_user_placeholder": "Search users",
+  "repo.issues.filter_by_username_placeholder": "Filter by username…",
   "repo.issues.filter_user_no_select": "All users",
   "repo.issues.filter_type": "Type",
   "repo.issues.filter_type.all_issues": "All issues",

templates/repo/issue/filter_item_user_fetch.tmpl

@@ -1,12 +1,12 @@
 {{/* This is a user list for filter, the data is provided by a remote "fetch" request
 * QueryParamKey: eg: "poster", "assignee"
 * QueryLink
-* UserSearchUrl
+* UserSearchUrl: if not set, no remote search, the inputed username will be used as navigation link's query param value
 * SelectedUsername
 * TextFilterTitle
 */}}
 {{$queryLink := .QueryLink}}
-<div class="item ui dropdown custom" data-tooltip-content="{{ctx.Locale.Tr "repo.user_search_tooltip"}}" data-global-init="initDropdownUserRemoteSearch"
+<div class="item ui dropdown custom" {{if $.UserSearchUrl}}data-tooltip-content="{{ctx.Locale.Tr "repo.user_search_tooltip"}}"{{end}} data-global-init="initDropdownUserRemoteSearch"
 		data-search-url="{{$.UserSearchUrl}}"
 		data-selected-username="{{$.SelectedUsername}}"
 		data-action-jump-url="{{QueryBuild $queryLink $.QueryParamKey NIL}}&{{$.QueryParamKey}}={username}"
@@ -15,7 +15,7 @@
 	<div class="menu">
 		<div class="ui icon search input">
 			<i class="icon">{{svg "octicon-search" 16}}</i>
-			<input type="text" placeholder="{{ctx.Locale.Tr "repo.issues.filter_user_placeholder"}}">
+			<input type="text" placeholder="{{ctx.Locale.Tr (Iif $.UserSearchUrl "repo.issues.filter_user_placeholder" "repo.issues.filter_by_username_placeholder")}}">
 		</div>
 		<a class="item" data-value="">{{ctx.Locale.Tr "repo.issues.filter_user_no_select"}}</a>
 		<a class="item item-from-input tw-hidden"></a>

web_src/js/features/repo-issue-list.ts

@@ -93,7 +93,7 @@ function initDropdownUserRemoteSearch(el: Element) {
 
   const selectUsername = (username: string) => {
     queryElems(elMenu, '.item.active, .item.selected', (el) => el.classList.remove('active', 'selected'));
-    elMenu.querySelector(`.item[data-value="${CSS.escape(username)}"]`)?.classList.add('selected');
+    elMenu.querySelector(`.item[data-value="${CSS.escape(username)}"]`)?.classList.add('active');
   };
 
   const processedResults: ProcessedIssuePoster[] = []; // to be used by dropdown to generate menu items
@@ -109,6 +109,7 @@ function initDropdownUserRemoteSearch(el: Element) {
   elSearchInput.value = selectedUsername;
   if (!searchUrl) {
     elSearchInput.addEventListener('input', syncItemFromInput);
+    syncItemFromInput();
     return;
   }