chore: Add EditorConfig for consistent code formatting

Introduces .editorconfig file to standardize formatting across editors.
Defines charset, line endings, indentation (spaces/tabs), and
file-specific rules for HTML, YAML, LICENSE, and Makefiles.

.editorconfig

@@ -0,0 +1,23 @@
+# https://editorconfig.org
+
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_size = 4
+indent_style = space
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[{*.htm,*.html}]
+indent_size = 2
+
+[{*.yml,*.yaml}]
+indent_size = 2
+
+[LICENSE]
+insert_final_newline = false
+
+[Makefile]
+indent_style = tab