Fix Discord message rendering: remove stray blockquote character

The empty blockquote line after the repo name was rendering as a literal ">" in Discord. Add a trailing space so it renders as a blank line within the blockquote instead.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

packages/spike/src/bridge/webhook-handler.ts

@@ -116,8 +116,8 @@ class PRHandler {
     let message = `
   > ### [${pullRequest.title}](<${pullRequest.html_url}>)
   > **${repositoryFullName}**
-  >
-  ${body
+> 
+${body
     .split("\n")
     .map((line) => `> ${line}`)
     .join("\n")}