feat(web): add plugin install dropdown to sidebar with context-based action dispatch

Add '+' dropdown menu to plugins sidebar category with three install
options: marketplace, upload local, and install from GitHub. Use shared
React context (pendingPluginInstallAction) instead of URL params to
reliably trigger install actions across components. Add e.stopPropagation
on all DropdownMenuItem handlers to prevent React portal event bubbling
from triggering parent SidebarMenuButton navigation.

web/src/app/home/components/home-sidebar/SidebarDataContext.tsx

@@ -30,6 +30,9 @@ export interface SidebarEntityItem {
   debug?: boolean;
 }
 
+// Install action types that can be triggered from sidebar
+export type PluginInstallAction = 'local' | 'github' | null;
+
 // Entity lists and refresh functions exposed via context
 export interface SidebarDataContextValue {
   bots: SidebarEntityItem[];
@@ -46,6 +49,9 @@ export interface SidebarDataContextValue {
   // Breadcrumb: entity name shown when viewing a detail page
   detailEntityName: string | null;
   setDetailEntityName: (name: string | null) => void;
+  // Pending plugin install action triggered from sidebar
+  pendingPluginInstallAction: PluginInstallAction;
+  setPendingPluginInstallAction: (action: PluginInstallAction) => void;
 }
 
 const SidebarDataContext = createContext<SidebarDataContextValue | null>(null);
@@ -61,6 +67,8 @@ export function SidebarDataProvider({
   const [plugins, setPlugins] = useState<SidebarEntityItem[]>([]);
   const [mcpServers, setMCPServers] = useState<SidebarEntityItem[]>([]);
   const [detailEntityName, setDetailEntityName] = useState<string | null>(null);
+  const [pendingPluginInstallAction, setPendingPluginInstallAction] =
+    useState<PluginInstallAction>(null);
 
   const refreshBots = useCallback(async () => {
     try {
@@ -216,6 +224,8 @@ export function SidebarDataProvider({
         refreshAll,
         detailEntityName,
         setDetailEntityName,
+        pendingPluginInstallAction,
+        setPendingPluginInstallAction,
       }}
     >
       {children}