Chore/add demo and verification docs

[AAdewunmi]

Summary

Adds reviewer-facing demo and final verification documentation for the StudyBuddy MVP.

Changes

• Added a complete MVP demo script for walking through the product journey.
• Updated final verification guidance with local, CI, deployment, and live Render checks.
• Documented the expected signup, dashboard, session, note, insight, logout, and protected-route flow.
• Captured the evidence checklist for Docker, tests, coverage, production settings, static assets, health checks, and Render runtime configuration.

Behaviour

Reviewers can now assess the MVP through two clear paths:

• docs/demo-script.md explains the product experience.
• docs/final-verification.md explains how to prove the implementation and deployment are working.

Why

This separates product narrative from technical verification, making the MVP easier to review, demo, and release-check.

Validation

• Verified docs align with current /users/, /dashboard/, /sessions/, /insights/, and /health/ routes.
• Verified final checklist matches Docker-backed local verification and Render deployment contract.
• Confirmed stale fixed test counts were removed from final verification guidance.

Result

The MVP now has a repeatable reviewer journey and evidence checklist for assessing product readiness.

Notes

Live Render verification still depends on the deployed service URL routing correctly.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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