add justfile

Justfile

@@ -0,0 +1,11 @@
+port := "8080"
+export TREEHOUSE_SITE := "http://localhost:" + port
+
+serve:
+    cargo watch -- cargo run -- serve --port {{port}}
+
+fix:
+    cargo run -- fix-all --apply
+
+ulid:
+    cargo run -- ulid