fix: address review feedback — gofmt NITs and remove unreachable default

- github/client.go: add missing blank line between doRequestWithBody and doJSONRequest
- cmd/review-bot/main.go: remove double blank line before findAllOwnReviews
- cmd/review-bot/main.go: remove unreachable default case in VCS client init switch
  (provider is already validated at startup)
- cmd/review-bot/main_test.go: remove double blank line before TestHasSharedToken
- cmd/review-bot/main_test.go: fix comment alignment (gofmt)
- review/persona_test.go: fix comment alignment in table literal (gofmt)

github/client.go

@@ -386,6 +386,7 @@ func (c *Client) doRequestWithBody(ctx context.Context, method, reqURL string, r
 	return c.doRequestCore(ctx, method, reqURL, opts)
 
 }
+
 // doJSONRequest performs an HTTP request with a JSON body and returns the response body.
 // It delegates retry/backoff/429 handling to doRequestWithBody.
 // This is a general-purpose helper used by any method that needs to send JSON payloads