fix: use import type for GraphConfig, remove verbatim-module-syntax exclusion

The verbatim-module-syntax lint rule was correctly flagging that
GraphConfig is only used in a type position (typeof GraphConfig). Since
typeof resolves purely at the type level, import type works fine here
and is the correct form. No lint exclusion needed.

Also: deno fmt across all files (markdown line wrapping).

mod.ts

@@ -1 +1 @@
-export * from "./src/graphs/mod.ts";
+export * from "./src/graphs/mod.ts";