[ravimahatonp]

Summary of Changes

This PR implements a robust, dependency-free Redis caching layer to cache frequently accessed historical ledgers and Horizon queries, resolving redundant network calls and rate-limiting bottlenecks.

Key Features:

• Native RESP Protocol Client (NativeRedisClient): Implemented lightweight Redis RESP protocol parser over Node's native net socket module with zero external npm dependencies.
• Graceful In-Memory Fallback: Seamlessly falls back to an in-memory TTL cache when Redis is unavailable, ensuring offline resilience and predictable testing.
• Ledger-Specific Cache Helpers:
  • setLedger(ledger): Stores ledger by sequence and hash with configurable TTL (default 24h for immutable ledgers).
  • getLedger(sequenceOrHash): Fast indexed lookup.
  • getOrFetchLedger(sequence, fetchFn): Read-through cache helper that queries Horizon only on cache misses.
• Runtime Metrics & Hit Ratio: Tracks total hits, misses, hit ratio, active backend, and connection status.
• Unit & Integration Tests: Added 14 unit and integration tests in tests/cache/redisCache.test.ts (100% passing).
• Usage Example Demo: Added executable example in examples/redis-cache-demo.ts.

Closes #73