docs: optimize playwright configuration and contribution doc (#2237)

Co-authored-by: Willow (GHOST) <git@willow.sh>
Co-authored-by: Willow (GHOST) <ghostdevbusiness@gmail.com>

Author: ShroXd

CONTRIBUTING.md

@@ -752,6 +752,23 @@ pnpm test:browser:ui     # Run with Playwright UI
 
 Make sure to read about [Playwright best practices](https://playwright.dev/docs/best-practices) and don't rely on classes/IDs but try to follow user-replicable behaviour (like selecting an element based on text content instead).
 
+#### Updating snapshots
+
+Some tests use image snapshots that must match the CI environment (Linux). If you need to update them, and aren't running Linux, you can use Docker to run in the same environment:
+
+```bash
+docker run --rm \
+  -e CI=true \
+  -e NODE_OPTIONS="--max-old-space-size=4096" \
+  -v $(pwd):/work \
+  -w /work \
+  mcr.microsoft.com/playwright:v1.58.2-noble \
+  sh -c "npm install -g pnpm && pnpm install && pnpm vp run build:test && pnpm vp run test:browser:prebuilt --update-snapshots"
+```
+
+> [!NOTE]
+> If the build runs out of memory, increase `--max-old-space-size` to `8192`.
+
 ### Test fixtures (mocking external APIs)
 
 E2E tests use a fixture system to mock external API requests, ensuring tests are deterministic and don't hit real APIs. This is handled at two levels:

playwright.config.ts

@@ -15,7 +15,7 @@ export default defineConfig<ConfigOptions>({
   webServer: {
     command: 'pnpm start:playwright:webserver',
     url: baseURL,
-    reuseExistingServer: false,
+    reuseExistingServer: !process.env.CI,
     timeout: 60_000,
   },
   // Start/stop mock connector server before/after all tests (teardown via returned closure)