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.

pkg/spec-api/package.json

@@ -0,0 +1,17 @@
+{
+  "name": "@uatu/spec",
+  "version": "0.0.1",
+  "description": "TypeScript spec API for Uatu (vendored locally; not published to npm in v0.1).",
+  "private": true,
+  "type": "module",
+  "main": "src/index.ts",
+  "types": "src/index.ts",
+  "scripts": {
+    "check": "tsc --noEmit",
+    "test": "node --test --experimental-strip-types test/*.test.ts"
+  },
+  "devDependencies": {
+    "@types/node": "^22.7.5",
+    "typescript": "^5.6.3"
+  }
+}