refactor(middleware): remove retry and circuit breaker logic

[itzlambda]

Changes Made

• Removed retry logic:

  • Deleted RetryPolicy enum and all retry-related configuration
  • Removed exponential backoff, fixed delay, and API-guided retry strategies
  • Cleaned up retry-related methods from ProviderConfig trait

• Removed circuit breaker functionality:

  • Eliminated circuit breaker middleware from the stack
  • Removed circuit breaker configuration options

• Simplified middleware stack to focus on:

  • Rate limiting
  • Timeouts
  • Connection pooling
  • Logging and metrics

• Updated dependencies:

  • Removed retry feature from Tower in Cargo.toml

• Documentation updates:

  • Updated CLAUDE.md to reflect simplified middleware architecture
  • Removed references to retry/circuit breaker from all example documentation
  • Deleted retry_policy_example.rs
  • Simplified middleware_usage.rs example