Extract issue number in /fix skill to support org/repo#number format (#8624)

The gh CLI doesn't accept "#8622" format directly.
Parse the issue number from $ARGUMENTS before passing to gh issue view,
matching the extraction already used elsewhere in the skill.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: iHiD

.claude/skills/fix/SKILL.md

@@ -13,7 +13,7 @@ You are fixing a GitHub issue for the exercism/website repository.
 ## Issue details
 
 ```json
-!`gh issue view $ARGUMENTS --json number,title,body,labels,comments`
+!`gh issue view $(echo "$ARGUMENTS" | grep -oE '[0-9]+$') --json number,title,body,labels,comments`
 ```
 
 Issue number: !`echo "$ARGUMENTS" | grep -oE '[0-9]+$'`