tools: add a basic .editorconfig

.editorconfig

@@ -0,0 +1,47 @@
+# EditorConfig is awesome: https://EditorConfig.org
+
+# top-most EditorConfig file
+root = true
+
+# Unix-style newlines with a newline ending every file
+[*]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+# Go files - use tabs (Go standard)
+[*.go]
+indent_style = tab
+indent_size = 4
+
+# Go mod files
+[go.{mod,sum}]
+indent_style = tab
+indent_size = 4
+
+# Makefiles - must use tabs
+[{Makefile,*.mk}]
+indent_style = tab
+indent_size = 4
+
+# YAML files
+[*.{yml,yaml}]
+indent_style = space
+indent_size = 2
+
+# JSON files
+[*.json]
+indent_style = space
+indent_size = 2
+
+# Markdown files
+[*.md]
+indent_style = space
+indent_size = 2
+trim_trailing_whitespace = false
+
+# Shell scripts
+[*.sh]
+indent_style = space
+indent_size = 2