feat(home): implement count for home auth dispatch requests and enable usage statistics

- Added `count` attribute to `homeAuthCount` requests to improve home message batching.
- Enabled usage statistics for home mode by default and added config-level enforcement.
- Adjusted failure logging to include detailed metadata in `UsageReporter`.
- Updated multiple executors to pass error details to `PublishFailure` for better debugging.
- Enhanced unit tests to validate `count` behavior and usage statistics enforcement across components.

internal/home/requests.go

@@ -3,6 +3,7 @@ package home
 type authDispatchRequest struct {
 	Type      string            `json:"type"`
 	Model     string            `json:"model"`
+	Count     int               `json:"count"`
 	SessionID string            `json:"session_id,omitempty"`
 	Headers   map[string]string `json:"headers,omitempty"`
 }