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).

deno.json

@@ -22,7 +22,7 @@
   },
   "lint": {
     "rules": {
-      "exclude": ["no-slow-types", "verbatim-module-syntax"]
+      "exclude": ["no-slow-types"]
     }
   },
   "tasks": {
@@ -33,4 +33,4 @@
     "fmt": "deno fmt",
     "publish:dry": "deno publish --allow-slow-types --dry-run"
   }
-}
+}