fix(database): add retry logic for PostgreSQL connection pool

[MerlinTheWhiz]

Description

Add automatic retry logic with exponential backoff and a circuit breaker to the PostgreSQL connection pool. When a transient connection error occurs, the pool now:

• Retries failed queries up to 3 times using retryWithBackoff() from src/utils/errorUtils.ts
• Automatically reconnects on idle client errors via the pool's error event
• Queues queries issued during the reconnect window and processes them once the connection is restored
• Trips a circuit breaker after 5 consecutive failures, immediately returning a 503 error for subsequent queries
• Resets the circuit breaker after a 60-second cooldown period or upon a successful new connection

Related Issue

Closes #739

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update

Checklist

• Code follows project style guidelines
• Self-review completed
• No console errors
• Uses Lucide icons consistently
• Responsive design implemented
• Starknet best practices followed

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