refactor(claude-code-hooks): extract handlers and session state

Split hook into per-concern modules:
- handlers/ directory for individual hook handlers
- session-hook-state.ts: session-level hook state management

src/hooks/claude-code-hooks/session-hook-state.ts

@@ -0,0 +1,11 @@
+export const sessionFirstMessageProcessed = new Set<string>()
+
+export const sessionErrorState = new Map<string, { hasError: boolean; errorMessage?: string }>()
+
+export const sessionInterruptState = new Map<string, { interrupted: boolean }>()
+
+export function clearSessionHookState(sessionID: string): void {
+	sessionErrorState.delete(sessionID)
+	sessionInterruptState.delete(sessionID)
+	sessionFirstMessageProcessed.delete(sessionID)
+}