feat: add local storage bookmark functionality

[NiranjanDoijode23]

Related Issue

Fixes #89

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Description

Added a "Save for Later / Bookmark" feature allowing students to easily save topics and access them via a dedicated Bookmarks page. This heavily improves UX by preventing students from having to manually navigate deep into semester folders to find their current reading position.

Changes made:

• Created useBookmarks.ts custom hook utilizing localStorage for state persistence.
• Built a reusable BookmarkButton.tsx component.
• Created a /bookmarks page to display and manage saved topics.
• Added a BOOKMARKS link to both desktop and mobile Navbars.
• Integrated the BookmarkButton into the DSC subject pages (and others).

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Type of Change

• Bug fix
• New feature
• Documentation update
• UI/UX improvement
• Refactor

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Screenshots / Demo

Before - Bookmarks tab And No save option

After - Added Bookmark tab and Save option To continue reading

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How Has This Been Tested?

• Tested locally using npm run dev.
• Verified that localStorage persists data across page reloads and browser restarts.
• Tested responsive design on the Bookmarks page and Mobile Navbar.

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Checklist

• My code follows the project structure and conventions
• I have tested the changes locally
• I have linked the related issue properly
• I have added screenshots where applicable
• No existing functionality was broken

[vercel]

@NiranjanDoijode23 is attempting to deploy a commit to the PushkarScripts Team on Vercel.

A member of the Team first needs to authorize it.

[NiranjanDoijode23]

Hii @pushkarscripts Also Assign me Issue #108 i will resolve the issue related to params in all the sems and subject

[NiranjanDoijode23]

Hii @pushkarscripts Assign me A Runtime Bug #108 and Feature #117 i would like to work on it

[pushkarscripts]

A few more things to improve here before this can be merged:

• The /bookmarks page currently feels disconnected from the rest of the app. Please add the common navbar/footer layout there as well so it stays visually consistent with the project.

• The bookmark button and its placement also feels slightly off right now and breaks the visual flow of the page. Try positioning it more cleanly near the navigation actions/header area instead (similar to the attached reference).
  

• Please also clean up unrelated/noisy changes in this PR (duplicate JSX/imports, repeated blocks, unnecessary formatting changes, etc.) to keep the review focused only on the bookmark feature.

• issues.json also seems unrelated to this feature and should not be committed.

[NiranjanDoijode23]

Hi @pushkarscripts,
I've successfully resolved the merge conflicts that occurred due to the recent Quiz updates.
I made sure to cleanly combine both the new ChapterQuizInline imports and my BookmarkButton imports so everything functions perfectly together.
The PR is now fully up to date with the latest main branch and ready for your review whenever you have the time! Let me know if you need any other changes