feat(codersdk): add circuit breaker configuration support for aibridge (#21546)

## Summary

Add circuit breaker support for AI Bridge to protect against cascading
failures from upstream AI provider rate limits (HTTP 429, 503, and
Anthropic's 529 overloaded responses).

## Changes

- Add 5 new CLI options for circuit breaker configuration:
  - `--aibridge-circuit-breaker-enabled` (default: false)
  - `--aibridge-circuit-breaker-failure-threshold` (default: 5)
  - `--aibridge-circuit-breaker-interval` (default: 10s)
  - `--aibridge-circuit-breaker-timeout` (default: 30s)
  - `--aibridge-circuit-breaker-max-requests` (default: 3)
- Update aibridge dependency to include circuit breaker support
- Add tests for pool creation with circuit breaker providers

## Notes

- Circuit breaker is **disabled by default** for backward compatibility
- When enabled, applies to both OpenAI and Anthropic providers
- Uses sony/gobreaker internally via the aibridge library

## Testing

```
make test RUN=TestPoolWithCircuitBreakerProviders
```

docs/reference/api/general.md

@@ -185,6 +185,11 @@ curl -X GET http://coder-server:8080/api/v2/deployment/config \
           "region": "string",
           "small_fast_model": "string"
         },
+        "circuit_breaker_enabled": true,
+        "circuit_breaker_failure_threshold": 0,
+        "circuit_breaker_interval": 0,
+        "circuit_breaker_max_requests": 0,
+        "circuit_breaker_timeout": 0,
         "enabled": true,
         "inject_coder_mcp_tools": true,
         "max_concurrency": 0,