feat(p2p): add circuit breaker to p2p client

[glottologist]

Describe the changes
Before:
P2P client made unbounded requests to failing peers.

After:
Implements circuit breaker pattern for peer connections. Failed peers are temporarily isolated, preventing cascade failures and improving network resilience.

Changes

Circuit Breaker Implementation

• Added CircuitBreakerManager<K> with atomic state management and capacity enforcement
• Three states: Closed (normal), Open (blocked after threshold failures), HalfOpen (testing recovery)
• Configurable failure threshold (5), cooldown duration (30s), and recovery attempts (3)

P2P Integration

• GossipClient tracks circuit breakers per peer mining address
• check_health() returns false when circuit is open
• Data retrieval operations (get_data, pull_data) check circuit breaker before requests
• Success/failure recorded on all peer interactions to update circuit state

Related Issue(s)
Please link to the issue(s) that will be closed with this PR.

Checklist

• Tests have been added/updated for the changes.
• Documentation has been updated for the changes (if applicable).
• The code follows Rust's style guidelines.

Additional Context
Add any other context about the pull request here.