chore(config): add exports field to module metadata

- Introduces an `exports` field to map module entry points

deno.jsonc

@@ -1,6 +1,9 @@
 {
     "name": "@0xmax42/http-kernel",
     "description": "A simple HTTP kernel for Deno",
+    "exports": {
+        "./mod.ts": "./src/mod.ts"
+    },
     "tasks": {
         "test": "deno test --allow-net --allow-env --unstable-kv --allow-read --allow-write --coverage **/__tests__/*.test.ts",
         "test:watch": "deno test --watch --allow-net --allow-env --unstable-kv --allow-read --allow-write **/__tests__/*.test.ts"