fix: make npm test build first, and approve esbuild's install script

Two problems that a maintainer hits on a clean checkout.

1. `npm test` needed a build before it, and it did not say so.
   `tests/bundle.test.ts` imports the package root (`import esmLibrary from
   '..'`), which package.json resolves to `release/`. On a checkout where
   `release/` is absent, that one suite fails:

       Error: Cannot find module '..' imported from tests/bundle.test.ts

   The test workflow hid the problem, because it runs `npm run build` before
   `npm test`. A maintainer who runs `npm ci && npm test` sees the failure.

   A `pretest` script now builds first, so `npm test` is correct in any order.
   `npm ci && npm test` passes on a clean clone.

2. npm 11 blocked esbuild's postinstall, and every install printed a warning:

       npm warn install-scripts 1 package has install scripts not yet covered
       npm warn install-scripts   esbuild@0.19.7 (postinstall: node install.js)

   esbuild still worked here, because @esbuild/win32-x64 and its siblings carry
   the binary, and the postinstall is a fallback. The warning is still noise on
   every install, and the fallback matters on a platform whose binary package
   npm does not select. `allowScripts` now approves that one package, pinned to
   the version that `overrides.tsup.esbuild` holds, so a change of the pin asks
   for the approval again.

Verified in linux containers on node 20, 22 and 24, and on windows: `npm ci`
then `npm test` gives 11 test files and 54 tests passed, no install warning,
and release/cjs/lossless.cjs and release/cjs/lossless.cjs.map stay
byte-identical to the files that cornerstonejs/codecs vendors.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: wayfarer3130

package.json

@@ -33,6 +33,7 @@
   },
   "scripts": {
     "test": "vitest run",
+    "pretest": "npm run build",
     "build": "tsup",
     "lint": "eslint .",
     "prepublishOnly": "npm run build"
@@ -63,5 +64,8 @@
     "tsup": {
       "esbuild": "0.19.7"
     }
+  },
+  "allowScripts": {
+    "esbuild@0.19.7": true
   }
 }