Preserve prebuilt dist during release gate (#210)

## Summary

- serve the release workflow's already-built `dist` from the production
Playwright gate
- preserve the existing auto-build behavior for standalone local
production tests
- keep the pre/post `dist` inventory guard strict and unchanged

## Root cause

The release workflow built and fingerprinted `dist`, but Playwright then
launched `preview:prod`, which ran a second Vite build. Timestamped
build metadata changed hashed chunks and caused the integrity comparison
to fail after all 26 production browser tests had passed.

## Verification

- production Playwright gate: 26/26 passed
- pre/post inventory: 735 files, zero changes
- release package validation: 735 files passed
- ESLint passed
- Prettier passed
- release package unit tests: 7/7 passed
- workflow YAML parsed successfully
- no test files changed

Co-authored-by: Jeppe Bundgaard <jb@truckwash.dk>

.github/workflows/release.yml

@@ -111,6 +111,7 @@ jobs:
         if: steps.branch-head.outputs.current == 'true'
         run: npm run test:e2e:prod
         env:
+          PLAYWRIGHT_PROD_PREBUILT: "1"
           PLAYWRIGHT_PROD_WEBKIT: "0"
 
       - name: Confirm production gate did not mutate dist

playwright.prod.config.ts

@@ -3,6 +3,11 @@ import { defineConfig, devices } from "@playwright/test";
 
 const baseURL = "http://127.0.0.1:4173";
 const isCI = !!process.env.CI;
+const usePrebuiltDist = ["1", "true"].includes(
+  String(process.env.PLAYWRIGHT_PROD_PREBUILT || "")
+    .trim()
+    .toLowerCase()
+);
 
 process.env.PLAYWRIGHT_BASE_URL = baseURL;
 
@@ -73,7 +78,7 @@ export default defineConfig({
     video: "retain-on-failure",
   },
   webServer: {
-    command: "npm run preview:prod",
+    command: usePrebuiltDist ? "npm run preview -- --host 127.0.0.1 --port 4173" : "npm run preview:prod",
     url: baseURL,
     timeout: 240_000,
     reuseExistingServer: !isCI,