Use wrapper script for label operations in issue triage (#968)

* Use wrapper script for label operations in issue triage

Updates /label-issue command and examples to use a dedicated
edit-issue-labels.sh script for label operations instead of raw
gh issue edit. The script validates labels against the repo's existing
labels before applying them. Also tightens gh search permission to
gh search issues.

* Show multiple --add-label flags in label-issue example

docs/solutions.md

@@ -415,12 +415,12 @@ jobs:
             4. Check if it duplicates existing issues
 
             Based on your analysis, add the appropriate labels using:
-            `gh issue edit [number] --add-label "label1,label2"`
+            `./scripts/edit-issue-labels.sh --issue [number] --add-label "label1" --add-label "label2"`
 
             If it appears to be a duplicate, post a comment mentioning the original issue.
 
           claude_args: |
-            --allowedTools "Bash(gh issue:*),Bash(gh search:*)"
+            --allowedTools "Bash(gh issue view:*),Bash(gh search issues:*),Bash(./scripts/edit-issue-labels.sh:*)"
 ```
 
 **Key Configuration:**