feat(ai): Implement Document Chat & Summarization (RAG)

[rach-kanc]

Description

This Pull Request introduces a native Document Chat feature using Retrieval-Augmented Generation (RAG).

Motivation: Students needed a way to extract insights and generate study materials from long PDFs without leaving the platform or hitting context-window limits in the standard AI Tutor.
Context: We enabled pgvector on Supabase to store document embeddings. PDFs are now parsed server-side using pdf-parse, chunked, and embedded using Gemini's text-embedding-004 model. A new split-screen UI was built so students can view the document and chat with the AI simultaneously.

Related Issue: Closes #78

Type of Change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

Note: This project does not currently have an automated test suite. The following manual verification was performed:

• API Route Testing: Uploaded a sample PDF and verified the text was successfully extracted, chunked, and embedded into the Supabase document_chunks table without breaking the max duration limit.
• RPC Function Testing: Ran similarity searches using the match_document_chunks Postgres function to ensure relevant context is fetched for user queries.
• UI Testing: Verified the split-screen UI renders correctly on desktop and mobile, and the PDF loads properly in the iframe viewer.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings/lint errors
• I have checked that my branch is up-to-date with main
• All tests pass locally with my changes (N/A - no local tests exist)

Tags

hard, ssoc26

[vercel]

@rach-kanc is attempting to deploy a commit to the vishwamistrylearning-1037's projects Team on Vercel.

A member of the Team first needs to authorize it.

[rach-kanc]

@MistryVishwa Check the PR

[MistryVishwa]

@rach-kanc Please resolve the branch conflicts.

[rach-kanc]

@MistryVishwa fixed the conflicts 👍🏻