feat: add session-tools-store for tracking tool restrictions per session

In-memory Map-based store that records tool restriction objects (e.g.,
question: false) by sessionID when prompts are sent. This enables
retrieving the original session's tool parameters when background tasks
complete and need to notify the parent session.

src/shared/session-tools-store.ts

@@ -0,0 +1,14 @@
+const store = new Map<string, Record<string, boolean>>()
+
+export function setSessionTools(sessionID: string, tools: Record<string, boolean>): void {
+  store.set(sessionID, { ...tools })
+}
+
+export function getSessionTools(sessionID: string): Record<string, boolean> | undefined {
+  const tools = store.get(sessionID)
+  return tools ? { ...tools } : undefined
+}
+
+export function clearSessionTools(): void {
+  store.clear()
+}