feat: add scrollbar to Table of Contents for long articles

[vaani1127]

This PR adds a scrollbar to the Table of Contents component to improve usability for long articles.

Changes

• Modified components/TableContents.tsx to add scrollbar functionality

Why

• Prevents TOC from taking up excessive vertical space
• Improves navigation experience for articles with many headings

[dhananjay6561]

Hey @vaani1127 👋 — thanks so much for contributing to the project, really appreciate it!

Your PR looks great and has been marked for merging. Here's a quick note from the reviewer:

Adds max-h-[80vh] overflow-y-auto + fixes indentation. Close #275 as duplicate.

We'll get this merged in soon. Keep the great work coming! 🚀

[Copilot]

Pull request overview

Adds vertical scrolling to the desktop Table of Contents so very long heading lists don’t expand indefinitely, improving navigation for long articles.

Changes:

• Makes the desktop TOC <nav> scrollable via a max-height and overflow-y-auto.
• Minor formatting/indentation cleanup in handleItemClick.

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[Copilot]

Adding max-h-[80vh] overflow-y-auto to the TOC container changes tocRef.current.clientHeight to be capped at ~80vh, so the resizeHandler effect (which sets isList when clientHeight > window.innerHeight * 0.8) will never flip isList to true for long TOCs. This effectively makes the large-screen <select> fallback and the isList-based layout tweaks in components/post-body.tsx unreachable/always-false. If you still want isList to represent “content overflows”, compare scrollHeight vs clientHeight (or scrollHeight > clientHeight) instead; otherwise, consider removing the isList sizing effect/prop to avoid misleading state.

Suggested change

	<nav ref={tocRef} className="max-h-[80vh] overflow-y-auto pr-2">
	<ul className="pl-0 leading-5">
	<nav className="max-h-[80vh] overflow-y-auto pr-2">
	<ul ref={tocRef} className="pl-0 leading-5">