feat: add citation file for project metadata

Co-authored-by: Copilot <copilot@github.com>

Author: KhazP

.github/CITATION.cff

@@ -0,0 +1,16 @@
+cff-version: 1.2.0
+message: "If you use this project, please cite it using the metadata below."
+title: "vibe-coding-prompt-template"
+type: software
+authors:
+  - name: "KhazP"
+repository-code: "https://github.com/KhazP/vibe-coding-prompt-template"
+url: "https://github.com/KhazP/vibe-coding-prompt-template"
+license: "MIT"
+preferred-citation:
+  type: software
+  title: "vibe-coding-prompt-template"
+  authors:
+    - name: "KhazP"
+  url: "https://github.com/KhazP/vibe-coding-prompt-template"
+  year: 2026