Add security and git policies, make repo a model example

- Never commit secrets; comprehensive .gitignore with fetch URL
- Never force-push to main
- go mod tidy before committing
- make hooks target with Go repo detection
- Add .editorconfig, .prettierrc, .prettierignore
- Template files URL for new repo setup

.gitignore

@@ -1,5 +1,21 @@
+# OS
 .DS_Store
+Thumbs.db
+
+# Editors
 *.swp
 *.swo
 *~
+*.bak
+.idea/
+.vscode/
+*.sublime-*
+
+# Node
 node_modules/
+
+# Environment / secrets
+.env
+.env.*
+*.pem
+*.key