refactor: eliminate prop drilling in JailsPage with context provider

Replace multi-hop prop forwarding with a dedicated JailContext that manages
jail state and actions. This reduces coupling, simplifies the component hierarchy,
and makes the data flow more explicit.

Changes:
- Create JailContext.tsx with JailProvider and useJailContext hook
- Wrap JailsPage content with JailProvider to expose jail state
- Refactor JailOverviewSection to use useJailContext instead of props
- Remove 10 props from JailOverviewSection component signature
- Add comprehensive documentation on state ownership and prop drilling

Benefits:
- Eliminates unnecessary prop chains through intermediate components
- Makes component contracts clearer (no longer need to pass unrelated props)
- Simplifies future refactoring of jail-related functionality
- Sets a pattern for other page-scoped state management

Testing:
- TypeScript type check passes (tsc --noEmit)
- Frontend builds successfully
- Existing JailsPage tests pass with new context structure

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

frontend/src/pages/jails/JailContext.tsx

@@ -0,0 +1,52 @@
+/**
+ * Context for managing jail state and actions across the jails page.
+ * Eliminates prop drilling by providing jail data and operations to all descendants.
+ */
+
+import { createContext, useContext, useCallback, ReactNode } from "react";
+import { useJails } from "../../hooks/useJailList";
+import type { JailSummary } from "../../types/jail";
+
+interface JailContextValue {
+  jails: JailSummary[];
+  total: number;
+  loading: boolean;
+  error: string | null;
+  refresh: () => void;
+  startJail: (name: string) => Promise<void>;
+  stopJail: (name: string) => Promise<void>;
+  setIdle: (name: string, on: boolean) => Promise<void>;
+  reloadJail: (name: string) => Promise<void>;
+  reloadAll: () => Promise<void>;
+}
+
+const JailContext = createContext<JailContextValue | undefined>(undefined);
+
+interface JailProviderProps {
+  children: ReactNode;
+}
+
+/**
+ * Provider component for jail state. Wrap JailsPage and its children with this.
+ */
+export function JailProvider({ children }: JailProviderProps): React.JSX.Element {
+  const jailState = useJails();
+
+  const value: JailContextValue = useCallback(() => ({
+    ...jailState,
+  }), [jailState])() as JailContextValue;
+
+  return <JailContext.Provider value={value}>{children}</JailContext.Provider>;
+}
+
+/**
+ * Hook to access jail state and actions.
+ * Must be used within a JailProvider.
+ */
+export function useJailContext(): JailContextValue {
+  const context = useContext(JailContext);
+  if (!context) {
+    throw new Error("useJailContext must be used within a JailProvider");
+  }
+  return context;
+}