Refactor App.tsx from god component to context-based architecture

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/web/src/contexts/player-characters-context.tsx

@@ -0,0 +1,29 @@
+import { createContext, type ReactNode, useContext } from "react";
+import { usePlayerCharacters } from "../hooks/use-player-characters.js";
+
+type PlayerCharactersContextValue = ReturnType<typeof usePlayerCharacters>;
+
+const PlayerCharactersContext =
+	createContext<PlayerCharactersContextValue | null>(null);
+
+export function PlayerCharactersProvider({
+	children,
+}: {
+	children: ReactNode;
+}) {
+	const value = usePlayerCharacters();
+	return (
+		<PlayerCharactersContext.Provider value={value}>
+			{children}
+		</PlayerCharactersContext.Provider>
+	);
+}
+
+export function usePlayerCharactersContext(): PlayerCharactersContextValue {
+	const ctx = useContext(PlayerCharactersContext);
+	if (!ctx)
+		throw new Error(
+			"usePlayerCharactersContext requires PlayerCharactersProvider",
+		);
+	return ctx;
+}