Sort assignee picker: recent selections first, then alphabetical

Tracks most recently selected assignees in localStorage and sorts both
the issue properties and new issue dialog assignee lists accordingly.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

ui/src/lib/recent-assignees.ts

@@ -0,0 +1,36 @@
+const STORAGE_KEY = "paperclip:recent-assignees";
+const MAX_RECENT = 10;
+
+export function getRecentAssigneeIds(): string[] {
+  try {
+    const raw = localStorage.getItem(STORAGE_KEY);
+    if (!raw) return [];
+    const parsed = JSON.parse(raw);
+    return Array.isArray(parsed) ? parsed : [];
+  } catch {
+    return [];
+  }
+}
+
+export function trackRecentAssignee(agentId: string): void {
+  if (!agentId) return;
+  const recent = getRecentAssigneeIds().filter((id) => id !== agentId);
+  recent.unshift(agentId);
+  if (recent.length > MAX_RECENT) recent.length = MAX_RECENT;
+  localStorage.setItem(STORAGE_KEY, JSON.stringify(recent));
+}
+
+export function sortAgentsByRecency<T extends { id: string; name: string }>(
+  agents: T[],
+  recentIds: string[],
+): T[] {
+  const recentIndex = new Map(recentIds.map((id, i) => [id, i]));
+  return [...agents].sort((a, b) => {
+    const aRecent = recentIndex.get(a.id);
+    const bRecent = recentIndex.get(b.id);
+    if (aRecent !== undefined && bRecent !== undefined) return aRecent - bRecent;
+    if (aRecent !== undefined) return -1;
+    if (bRecent !== undefined) return 1;
+    return a.name.localeCompare(b.name);
+  });
+}