Add a SKILL and PROMPT for fixing a GitHub issue (#1558)

Signed-off-by: Cosmin Cojocar <cosmin@cojocar.ch>

.github/prompts/fix-gosec-bug-from-issue.prompt.md

@@ -0,0 +1,28 @@
+---
+name: Fix Gosec Bug From Issue
+mode: agent
+description: Investigate and fix a gosec bug from a GitHub issue URL using the reusable bug-fix skill.
+---
+
+Use the skill Fix Gosec Bug From Issue from .github/skills/gosec-fix-issue/SKILL.md.
+
+Follow the skill contract exactly:
+- First response must include only reproduction status on master (or blocker), root cause, detailed fix plan, and a confirmation request.
+- Do not start implementation until confirmation is explicitly provided.
+
+Issue input:
+
+### GitHub issue URL
+{{github_issue_url}}
+
+### gosec version (optional)
+{{gosec_version}}
+
+### Go version (optional)
+{{go_version}}
+
+### Operating system / Environment (optional)
+{{environment}}
+
+### Additional notes (optional)
+{{additional_notes}}