fix: trim whitespace from ParseTitle result

ParseTitle returned lang[start:] without trimming, so inputs like
'python title  My Title' returned '  My Title' with leading spaces.
The extra whitespace propagated into the rendered Confluence title
element. Add strings.TrimSpace to remove leading/trailing whitespace.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

renderer/fencedcodeblock.go

@@ -72,7 +72,7 @@ func ParseTitle(lang string) string {
 		// it's found, check if title is given and return it
 		start := index + 6
 		if len(lang) > start {
-			return lang[start:]
+			return strings.TrimSpace(lang[start:])
 		}
 	}
 	return ""