Add GitHub Copilot instructions and fix critical application bugs

[Copilot]

This PR adds comprehensive GitHub Copilot instructions for working with the KVStore distributed key-value store and fixes two critical bugs that prevented the application from running correctly.

New File: .github/copilot-instructions.md

The instructions provide complete guidance for developers working with this Go-based distributed system:

• Complete setup process: Dependencies (Go, ZooKeeper, Java), build instructions, and ZooKeeper configuration
• Architecture overview: Leader-follower pattern, 2-phase commit, Write-Ahead Logging, and distributed consensus
• Validation scenarios: End-to-end testing procedures including write operations and multi-node setup
• Common issues and solutions: Known problems like ZooKeeper node setup and WAL conflicts
• Development workflow: Best practices for distributed systems development
• Performance expectations: Build times (~0.4 seconds), startup behavior, and timeout recommendations

Critical Bug Fixes

1. Fixed ReplicationManager Constructor Call

File: cmd/http_api/main.go
Issue: The main function was passing 4 arguments to replication.NewReplicationManager() but the constructor only accepts 2.
Fix: Removed the extra WAL and cluster manager parameters that are initialized internally.

2. Fixed Blocking Cluster Manager Initialization

File: internal/cluster/manager.go
Issue: The InitializeClusterMetadata() method contained an infinite loop watching for ZooKeeper events, preventing the HTTP server from starting.
Fix: Moved the event watching loop into a separate goroutine so initialization completes and allows the server to start.

Additional Improvements

• Added .gitignore to exclude build artifacts (http_api) and runtime files (wal_*.log)
• All instructions have been thoroughly validated with complete end-to-end testing

These changes enable the distributed KVStore to start successfully, perform leader election, handle write operations, and maintain transaction logs through the Write-Ahead Log system.

Fixes #7.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• archive.apache.org
  • Triggering command: wget REDACTED (dns block)
• esm.ubuntu.com
  • Triggering command: /usr/lib/apt/methods/https (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

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✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.