feat: implement caching layer and roadmap db indexing

[ekelemepraise-code]

🚀 Feature Overview

This pull request implements two MVP-critical features for the Web3 Student Lab platform, targeting both the Soroban smart contract architecture and the React-based curriculum frontend.

Fixes Issues

• Closes [Smart Contract] Develop Caching Layer for Smart Contract Playground #786 - [Smart Contract] Develop Caching Layer for Smart Contract Playground
• Closes [Frontend] Implement Database Indexing for Web3 Learning Roadmap #785 - [Frontend] Implement Database Indexing for Web3 Learning Roadmap

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🛠️ Implementation Details

1. Smart Contract Caching Layer (#786)

Developed an on-chain caching mechanism to enhance the execution efficiency and overall user experience for the Smart Contract Playground module.

• Contract Created: contracts/src/playground_cache.rs
• Features:
  • Implemented core key-value persistent storage via the PlaygroundCacheContract.
  • Secured caching mutations (set_cache) behind administrative RBAC validation logic.
  • Added inline comprehensive test suites utilizing soroban_sdk::testutils to validate state hydration, administrative restrictions, and caching data accuracy.
  • Registered the new module safely within the contract lib.rs exports.

2. Frontend Roadmap Database Indexing (#785)

Integrated an offline-first indexed storage mechanism into the Web3 Learning Roadmap, converting it from a stateless component into a fully dynamic and persistent user journey tracking system.

• Database Manager Expanded: Upgraded the internal IndexedDB schema to DB_VERSION = 2 within DatabaseManager.ts by introducing the roadmap_nodes Object Store.
• Indexing Capabilities: Setup dual-indexing for node query tracking (status and updatedAt).
• Roadmap Component (page.tsx) Updated:
  • Refactored the UI component to securely hydrate progress from IndexedDB seamlessly on initialization.
  • Ensured dynamic user interactions automatically sync progression changes (IN_PROGRESS to COMPLETED) down to the newly-created local database layer.

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✅ Acceptance Criteria Validated

• Caching Layer feature is fully functional and passes all automated Soroban Rust tests.
• Roadmap Database Indexing is strictly typed and handles node progressions seamlessly.
• Implementation preserves backward compatibility with existing Web3 Learning Roadmap and Smart Contract Playground infrastructure.
• Code meets project style guidelines (TypeScript, Rust, Tailwind CSS).

🗂️ Checklist

• Performed a self-review of the code
• Verified local test suites pass (cargo test)
• Verified frontend build completes securely (npm run build)
• Minimal changes ensuring stability across existing implementations

Closes #786
Closes #792
Closes #788
Closes #785

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[ayomideadeniran]

Well implemented

[ayomideadeniran]

Still Under review