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/runtime/executor/antigravity_executor.go

@@ -898,7 +898,7 @@ attemptLoop:
 				}
 				if errScan := scanner.Err(); errScan != nil {
 					helps.RecordAPIResponseError(ctx, e.cfg, errScan)
-					reporter.PublishFailure(ctx)
+					reporter.PublishFailure(ctx, errScan)
 					out <- cliproxyexecutor.StreamChunk{Err: errScan}
 				} else {
 					reporter.EnsurePublished(ctx)
@@ -1374,7 +1374,7 @@ attemptLoop:
 				}
 				if errScan := scanner.Err(); errScan != nil {
 					helps.RecordAPIResponseError(ctx, e.cfg, errScan)
-					reporter.PublishFailure(ctx)
+					reporter.PublishFailure(ctx, errScan)
 					select {
 					case out <- cliproxyexecutor.StreamChunk{Err: errScan}:
 					case <-ctx.Done():