feat(ui): org chart page, issue detail tabs, and UX improvements

- Add org chart page with tree visualization and sidebar nav link
- Restructure issue detail into tabbed layout (comments/activity/sub-issues)
- Persist comment drafts to localStorage with debounce
- Add inline assignee picker to issues list with search
- Fix assignee clear to reset both agent and user assignee
- Fix InlineEditor nesting when rendering markdown content

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

ui/src/components/Sidebar.tsx

@@ -7,6 +7,7 @@ import {
   History,
   Search,
   SquarePen,
+  Network,
 } from "lucide-react";
 import { useQuery } from "@tanstack/react-query";
 import { SidebarSection } from "./SidebarSection";
@@ -90,6 +91,7 @@ export function Sidebar() {
           <SidebarAgents />
 
           <SidebarSection label="Company">
+            <SidebarNavItem to="/org" label="Org" icon={Network} />
             <SidebarNavItem to="/costs" label="Costs" icon={DollarSign} />
             <SidebarNavItem to="/activity" label="Activity" icon={History} />
           </SidebarSection>