feat(FN-3398): update desktop README with multi-project setup and troublesh

The merge lands Step 7 of FN-3398, adding documentation and delivery artifacts across the mobile and desktop packages with updated READMEs, mobile-specific docs, and architecture references.

Fusion-Task-Id: FN-3398

packages/dashboard/app/context/ShellContext.tsx

@@ -0,0 +1,55 @@
+import { createContext, useContext, useEffect, useMemo, useState, type PropsWithChildren } from "react";
+import type { FusionShellApi, ShellConnectionState } from "../types/native-shell";
+
+interface ShellContextValue {
+  shellApi: FusionShellApi | null;
+  state: ShellConnectionState;
+  ready: boolean;
+}
+
+const DEFAULT_STATE: ShellConnectionState = {
+  host: "web",
+  activeProfileId: null,
+  profiles: [],
+};
+
+const ShellContext = createContext<ShellContextValue>({
+  shellApi: null,
+  state: DEFAULT_STATE,
+  ready: true,
+});
+
+export function ShellProvider({ children }: PropsWithChildren) {
+  const shellApi = useMemo(() => (typeof window !== "undefined" ? window.fusionShell ?? null : null), []);
+  const [state, setState] = useState<ShellConnectionState>(DEFAULT_STATE);
+  const [ready, setReady] = useState(!shellApi);
+
+  useEffect(() => {
+    if (!shellApi) {
+      return;
+    }
+
+    let cancelled = false;
+    void shellApi.getState().then((value) => {
+      if (!cancelled) {
+        setState(value);
+        setReady(true);
+      }
+    });
+
+    const unsubscribe = shellApi.subscribe((nextState) => {
+      setState(nextState);
+    });
+
+    return () => {
+      cancelled = true;
+      unsubscribe();
+    };
+  }, [shellApi]);
+
+  return <ShellContext.Provider value={{ shellApi, state, ready }}>{children}</ShellContext.Provider>;
+}
+
+export function useShellContext(): ShellContextValue {
+  return useContext(ShellContext);
+}