feat(admin): add msh_single_admin project and harden ignore rules

Introduce the new Vue admin project into version control while tightening gitignore patterns to keep env files, logs, build artifacts, and test outputs out of commits.

Made-with: Cursor

msh_single_admin/.editorconfig

@@ -0,0 +1,14 @@
+# https://editorconfig.org
+root = true
+
+[*]
+charset = utf-8
+indent_style = space
+indent_size = 2
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[*.md]
+insert_final_newline = false
+trim_trailing_whitespace = false