fix: add missing useCallback dependency arrays in App.tsx

[kuishou68]

Closes #139\n\n## Problem\n\ngetNodes and getEdgeVisibility are used inside handleNext, handlePrev, and handleReset useCallback hooks but are not listed in their dependency arrays. This causes stale closure bugs and triggers react-hooks/exhaustive-deps ESLint violations.\n\n## Fix\n\nWrapped getNodes and getEdgeVisibility in useCallback with stable [] dependency arrays, then added them to the dependency arrays of the three affected handlers.