chore(spec-api): scaffold @uatu/spec package metadata

TypeScript 5.6 with strict mode, bundler module resolution. Tests
run via node --test --experimental-strip-types so we don't need
vitest or a build step. Adds node_modules to .gitignore.

.gitignore

@@ -19,3 +19,6 @@ local.properties
 
 # Uatu runs
 /runs/
+
+# Node
+node_modules/