Pushing to merge Reeces changes. Added the right rail and made minimal changes to the selection logic on page editor, file manager and thumbnail

frontend/src/contexts/RightRailContext.tsx

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+import React, { createContext, useCallback, useContext, useMemo, useState } from 'react';
+import { RightRailAction, RightRailButtonConfig } from '../types/rightRail';
+
+interface RightRailContextValue {
+	buttons: RightRailButtonConfig[];
+	actions: Record<string, RightRailAction>;
+	registerButtons: (buttons: RightRailButtonConfig[]) => void;
+	unregisterButtons: (ids: string[]) => void;
+	setAction: (id: string, action: RightRailAction) => void;
+	clear: () => void;
+}
+
+const RightRailContext = createContext<RightRailContextValue | undefined>(undefined);
+
+export function RightRailProvider({ children }: { children: React.ReactNode }) {
+	const [buttons, setButtons] = useState<RightRailButtonConfig[]>([]);
+	const [actions, setActions] = useState<Record<string, RightRailAction>>({});
+
+	const registerButtons = useCallback((newButtons: RightRailButtonConfig[]) => {
+		setButtons(prev => {
+			const merged = [...prev.filter(b => !newButtons.some(nb => nb.id === b.id)), ...newButtons];
+			return merged.sort((a, b) => (a.order || 0) - (b.order || 0));
+		});
+	}, []);
+
+	const unregisterButtons = useCallback((ids: string[]) => {
+		setButtons(prev => prev.filter(b => !ids.includes(b.id)));
+		setActions(prev => Object.fromEntries(Object.entries(prev).filter(([id]) => !ids.includes(id))));
+	}, []);
+
+	const setAction = useCallback((id: string, action: RightRailAction) => {
+		setActions(prev => ({ ...prev, [id]: action }));
+	}, []);
+
+	const clear = useCallback(() => {
+		setButtons([]);
+		setActions({});
+	}, []);
+
+	const value = useMemo<RightRailContextValue>(() => ({ buttons, actions, registerButtons, unregisterButtons, setAction, clear }), [buttons, actions, registerButtons, unregisterButtons, setAction, clear]);
+
+	return (
+		<RightRailContext.Provider value={value}>
+			{children}
+		</RightRailContext.Provider>
+	);
+}
+
+export function useRightRail() {
+	const ctx = useContext(RightRailContext);
+	if (!ctx) throw new Error('useRightRail must be used within RightRailProvider');
+	return ctx;
+}