refactor: format and remove unused values

- update format rules
- update plugin file headers
- remove unused opacity from palette

.editorconfig

@@ -0,0 +1,12 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_style = tab
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[*.lua]
+indent_size = 3
+indent_style = tab