feat(web): collapsible icon sidebar (persisted, auto-collapse on narrow) (#44, #58)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web/src/test/setup.ts

@@ -21,6 +21,25 @@ if (typeof globalThis.localStorage === "undefined") {
   });
 }
 
+// jsdom does not implement matchMedia. useMediaQuery (used by the shell
+// sidebar) calls it on mount, so provide a minimal non-matching stub.
+if (typeof window !== "undefined" && typeof window.matchMedia !== "function") {
+  Object.defineProperty(window, "matchMedia", {
+    value: (query: string): MediaQueryList =>
+      ({
+        matches: false,
+        media: query,
+        onchange: null,
+        addEventListener: () => {},
+        removeEventListener: () => {},
+        addListener: () => {},
+        removeListener: () => {},
+        dispatchEvent: () => false,
+      }) as MediaQueryList,
+    writable: true,
+  });
+}
+
 // Start MSW at module level so its fetch patch is in place before any test
 // module captures globalThis.fetch via openapi-fetch's createClient().
 server.listen({ onUnhandledRequest: "error" });