feat(sidebar): implement inbox sidebar with docked and floating modes, add sidebar context for state management

surfsense_web/components/layout/hooks/SidebarContext.tsx

@@ -0,0 +1,37 @@
+"use client";
+
+import { createContext, useContext, type ReactNode } from "react";
+
+interface SidebarContextValue {
+	isCollapsed: boolean;
+	setIsCollapsed: (collapsed: boolean) => void;
+	toggleCollapsed: () => void;
+}
+
+const SidebarContext = createContext<SidebarContextValue | null>(null);
+
+interface SidebarProviderProps {
+	children: ReactNode;
+	value: SidebarContextValue;
+}
+
+export function SidebarProvider({ children, value }: SidebarProviderProps) {
+	return <SidebarContext.Provider value={value}>{children}</SidebarContext.Provider>;
+}
+
+export function useSidebarContext(): SidebarContextValue {
+	const context = useContext(SidebarContext);
+	if (!context) {
+		throw new Error("useSidebarContext must be used within a SidebarProvider");
+	}
+	return context;
+}
+
+/**
+ * Safe version that returns null if not within provider
+ * Useful for components that may be rendered outside the sidebar context
+ */
+export function useSidebarContextSafe(): SidebarContextValue | null {
+	return useContext(SidebarContext);
+}
+