Implement cluster mode

[adelra]

No description provided.

[Copilot]

Pull Request Overview

This PR implements cluster mode support for the Fastbu cache server.

• Adds new modules (cluster, cluster_cache, api_cache, api_cache_trait) and adjusts the CLI to support cluster configuration.
• Updates the test script, configuration file, and Cargo.toml to support clustering.
• Enhances API integration to work with a cluster-aware cache.

Reviewed Changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
test_cluster.sh	Introduces a shell script to test running in cluster mode.
src/storage.rs	Adds tests to verify storage initialization and save operations.
src/main.rs	Refactors command-line parsing and integrates cluster mode initialization.
src/cluster_cache.rs	Implements a cluster-aware cache with message forwarding and direct TCP fetch.
src/cache.rs	Makes cache entries public to support external access.
src/api_cache_trait.rs	Defines the ApiCache trait and its implementations for cache types.
src/api_cache.rs	Provides an API wrapper for the cluster cache.
src/api.rs	Refactors server startup to accept generic ApiCache types and adjusts endpoint implementations.
cluster.toml	Provides configuration for cluster mode including node and cache settings.
Cargo.toml	Adds dependencies necessary for cluster functionality.

Comments suppressed due to low confidence (1)

src/api_cache.rs:31

• Consider replacing 'std::io::Error::other(...)' with 'std::io::Error::new(std::io::ErrorKind::Other, ...)' to adhere to idiomatic error construction.

Err(std::io::Error::other(format("Cluster insert failed: {}", e)))