feat: add shared module quiz system

[mnaimfaizy]

Summary

This PR adds a shared end-of-module quiz system across the learning modules in Code Executives.

The implementation introduces a reusable timed quiz experience, wires it into every supported module as the final section, stores quiz-bank content in root-level JSON files, and documents both the runtime behavior and the authoring workflow for future maintenance.

What Changed

• Added a shared quiz domain model in src/types/quiz.ts.
• Added shared quiz utilities in src/utils/quiz.ts for bank loading, validation, grading, answer formatting, sampling, storage keys, and reference resolution.
• Added useQuizSession in src/shared/hooks/useQuizSession.ts to manage bank loading, timed attempts, localStorage persistence, hydration, navigation, and result history.
• Added reusable quiz UI components:
  • src/shared/components/quiz/ModuleQuizSection.tsx
  • src/shared/components/quiz/QuestionRenderer.tsx
• Added centralized module metadata and section navigation in src/shared/constants/moduleNavigation.ts.
• Updated the sidebar to use shared module navigation data and expose Quiz as the final module section.
• Integrated the quiz section into all supported learning modules:
  • JavaScript
  • RxJS
  • Git
  • Data Structures
  • React
  • Next.js
  • Big-O
  • Python
  • System Design
  • TypeScript
  • AI Fundamentals
  • Node.js
  • DevOps
  • Authentication & Authorization
• Added root-level quiz banks under quiz-banks/, one JSON file per module, with scenario-based question sets.
• Added .github/agents/module-quiz-generator.agent.md to support future bank generation and maintenance workflows.
• Updated project documentation:
  • README.md
  • docs/Project-Layout-and-Structure.md
  • docs/Quiz-System-Guide.md

Quiz Behavior

• Each run is timed to 10 minutes.
• Each run samples 5 questions from the module bank.
• Banks are structured for larger scenario-based question pools rather than fixed single-run quizzes.
• Results and active attempts are persisted in localStorage.
• Incorrect answers surface review links back into the relevant module sections.
• Recent local history is shown in the shared quiz UI.

Storage And Authoring Model

• Quiz banks live at the repository root in quiz-banks/{module}.quiz.json.
• Each module uses a clearly named bank file for easier maintenance and agent discovery.
• The new shared agent file documents how quiz banks should be created or updated without introducing duplicate questions or answers.

Validation

The branch was validated before opening this PR:

• npm run build
• npm run lint
• npm run test:run

Validation results:

• Build passed.
• Lint passed.
• Tests passed: 21 test files, 211 tests.

Notes

• The production build still reports existing Vite circular chunk warnings and chunk-size warnings, but the build completes successfully.
• This PR is focused on the shared quiz system, quiz-bank content, module integration, and supporting docs/authoring workflow.