fix: update frontend dependencies

[nrps9909]

Summary

• update LangChain, LangGraph, Groq, Express, and UUID dependencies to currently supported releases
• reduce the current npm audit result from 11 advisories (including 1 critical and 4 high) to zero
• add dependency compatibility tests for the exact LangGraph message/checkpoint flow used by EduAi
• verify that both the LangChain Groq client and direct Groq SDK still initialize without a network request

Addresses #54. This is intentionally stacked on #53 so the new quality workflow tests it; merge #53 before this pull request. After #53 reaches main, this pull request can be retargeted to main.

Validation

• npm ci --prefix frontend --ignore-scripts
• npm run check --prefix frontend (2/2 tests pass)
• npm audit --prefix frontend --audit-level=moderate (0 vulnerabilities)
• npm ls --all --omit=dev
• started the Express server with a non-secret test key
• confirmed the login page returns HTTP 200
• confirmed incomplete conversation requests return HTTP 400
• python3 -m compileall -q flask_server
• docker compose config --quiet
• git diff --check

Checklist

• I kept this pull request focused on one change.
• I tested the affected behavior.
• I did not include credentials, student data, recordings, or other private data.
• My contribution is compatible with the repository's GPL-3.0 license.

Prepared with Codex assistance; all listed validation ran against this branch.