chore: initialize the Go module and repository scaffolding

Add the Go module definition and lockfile, editor and ignore rules, and a Makefile with build, test, vet, install, and man targets. The version is injected at build time with -ldflags.

.editorconfig

@@ -0,0 +1,25 @@
+# See https://editorconfig.org for the format.
+
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+indent_style = tab
+indent_size = 4
+
+[*.go]
+indent_style = tab
+
+[*.{md,markdown,yml,yaml,json}]
+indent_style = space
+indent_size = 2
+
+[Makefile]
+indent_style = tab
+
+[*.1]
+indent_style = space
+indent_size = 2