Add shared UI primitives, contexts, and reusable components

Add shadcn components: avatar, breadcrumb, checkbox, collapsible,
command, dialog, dropdown-menu, label, popover, scroll-area, sheet,
skeleton, tabs, textarea, tooltip. Add shared components: BreadcrumbBar,
CommandPalette, CompanySwitcher, CommentThread, EmptyState, EntityRow,
FilterBar, InlineEditor, MetricCard, PageSkeleton, PriorityIcon,
PropertiesPanel, StatusIcon, SidebarNavItem/Section. Add contexts for
breadcrumbs, dialogs, and side panels. Add keyboard shortcut hook and
utility helpers. Update layout, sidebar, and main app shell.

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

ui/src/main.tsx

@@ -3,13 +3,25 @@ import { createRoot } from "react-dom/client";
 import { BrowserRouter } from "react-router-dom";
 import { App } from "./App";
 import { CompanyProvider } from "./context/CompanyContext";
+import { BreadcrumbProvider } from "./context/BreadcrumbContext";
+import { PanelProvider } from "./context/PanelContext";
+import { DialogProvider } from "./context/DialogContext";
+import { TooltipProvider } from "@/components/ui/tooltip";
 import "./index.css";
 
 createRoot(document.getElementById("root")!).render(
   <StrictMode>
     <CompanyProvider>
       <BrowserRouter>
-        <App />
+        <TooltipProvider>
+          <BreadcrumbProvider>
+            <PanelProvider>
+              <DialogProvider>
+                <App />
+              </DialogProvider>
+            </PanelProvider>
+          </BreadcrumbProvider>
+        </TooltipProvider>
       </BrowserRouter>
     </CompanyProvider>
   </StrictMode>