feat: update library READMEs and add working examples

[joshrotenberg]

Summary

This PR addresses issue #35 by updating both library READMEs and adding comprehensive working examples to improve developer experience.

Changes Made

📁 New Examples Added

• redis-cloud crate: Added examples/ directory with:

  • basic.rs - Basic connection and account information retrieval
  • database_management.rs - Database operations with proper handler usage

• redis-enterprise crate: Added examples/ directory with:

  • basic.rs - Cluster info, nodes, and database listing
  • database_management.rs - Database operations with statistics

📚 README Updates

• redis-cloud: Updated with current API patterns using CloudDatabaseHandler
• redis-enterprise: Updated with current API patterns using BdbHandler
• Fixed outdated examples that used non-existent methods
• Added proper environment variable configuration examples

🔧 API Pattern Improvements

• Cloud API: Showcases both typed methods (create()) and raw methods (create_raw())
• Enterprise API: Demonstrates proper use of typed structs vs raw JSON access
• Builder patterns: Shows correct client configuration using builders
• Handler usage: Examples use proper handler instantiation patterns

🏗️ Developer Experience Improvements

• All examples compile without warnings
• Environment variable based configuration for easy testing
• Commented-out creation examples to prevent accidental resource creation
• Proper error handling and type usage throughout

Key Technical Insights Addressed

1. Redis Cloud uses CloudDatabaseHandler::new(client) pattern with both typed and raw API methods
2. Redis Enterprise uses BdbHandler::new(client) pattern with fully typed responses
3. Client builders use different method names: Cloud uses standard methods, Enterprise uses base_url()
4. Proper distinction between raw JSON access vs typed struct access

Testing

• ✅ All examples compile cleanly with cargo check
• ✅ Passes cargo fmt and cargo clippy checks
• ✅ No unused imports or warnings

This significantly improves the developer onboarding experience for both Redis Cloud and Enterprise API clients.

Closes #35