fix(artifact): declare protobuf RPC runtime dependency

Prepare 6.3.1 and verify the packed production package in a clean consumer.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

scripts/test-package.mjs

@@ -0,0 +1,77 @@
+import assert from 'node:assert/strict'
+import {execFileSync} from 'node:child_process'
+import {mkdtempSync, readFileSync, rmSync} from 'node:fs'
+import {tmpdir} from 'node:os'
+import {join} from 'node:path'
+import {fileURLToPath} from 'node:url'
+
+const packageDirectory = fileURLToPath(new URL('../', import.meta.url))
+const npm = process.env.npm_execpath
+assert.ok(npm, 'Run this check with npm run test:package')
+
+const consumer = mkdtempSync(join(tmpdir(), 'artifact-package-'))
+const env = {...process.env}
+delete env.NODE_PATH
+
+function runNpm(args, cwd) {
+  return execFileSync(process.execPath, [npm, ...args], {
+    cwd,
+    env,
+    encoding: 'utf8'
+  })
+}
+
+try {
+  const [{filename}] = JSON.parse(
+    runNpm(
+      ['pack', '--json', '--ignore-scripts', '--pack-destination', consumer],
+      packageDirectory
+    )
+  )
+  runNpm(
+    [
+      'install',
+      '--omit=dev',
+      '--ignore-scripts',
+      '--no-audit',
+      '--no-fund',
+      '--package-lock=false',
+      join(consumer, filename)
+    ],
+    consumer
+  )
+
+  const manifest = JSON.parse(
+    readFileSync(
+      join(consumer, 'node_modules/@actions/artifact/package.json'),
+      'utf8'
+    )
+  )
+  assert.equal(manifest.dependencies['@protobuf-ts/runtime-rpc'], '^2.11.1')
+  execFileSync(
+    process.execPath,
+    [
+      '--input-type=module',
+      '--eval',
+      `
+        import assert from 'node:assert/strict'
+        import {createRequire} from 'node:module'
+        import client, {DefaultArtifactClient} from '@actions/artifact'
+        import {ServiceType} from '@protobuf-ts/runtime-rpc'
+
+        assert.ok(client instanceof DefaultArtifactClient)
+        assert.equal(typeof ServiceType, 'function')
+        const require = createRequire(import.meta.url)
+        assert.throws(() => require.resolve('@protobuf-ts/plugin'), {
+          code: 'MODULE_NOT_FOUND'
+        })
+      `
+    ],
+    {cwd: consumer, env, stdio: 'inherit'}
+  )
+  console.log(
+    'Packed artifact imports successfully with production dependencies'
+  )
+} finally {
+  rmSync(consumer, {recursive: true, force: true})
+}