Revert SwiftShader, consolidate maxDiffPixelRatio to global config

SwiftShader (CPU-based WebGL) is too slow for this app — screenshot
stabilization times out. Hardware GPU rendering is inherently
non-deterministic between CI runs, so maxDiffPixelRatio is necessary.

Consolidate tolerance to a single global 0.05 (was 0.03 global + 0.05
per-test for real_data/). Remove the per-test override and options
plumbing from expectScreenshot since all tests use the same tolerance.

Author: frewsxcv

.github/workflows/build.yml

@@ -81,9 +81,6 @@ jobs:
         run: cd www && npx playwright install --with-deps chromium
       - name: Run Playwright tests
         run: cd www && npx playwright test
-      - name: Update Playwright snapshots
-        if: failure()
-        run: cd www && npx playwright test --update-snapshots
       - name: Upload Playwright report
         uses: actions/upload-artifact@v4
         if: ${{ !cancelled() }}

www/playwright.config.ts

@@ -14,6 +14,8 @@ export default defineConfig({
 
   expect: {
     toHaveScreenshot: {
+      // Hardware GPU rendering is inherently non-deterministic between runs
+      maxDiffPixelRatio: 0.05,
       threshold: 0.2,
     },
   },
@@ -31,12 +33,7 @@ export default defineConfig({
         ...devices["Desktop Chrome"],
         viewport: { width: 1280, height: 720 },
         launchOptions: {
-          args: [
-            "--enable-gpu",
-            ...(process.env.CI
-              ? ["--use-angle=swiftshader"]
-              : ["--use-angle=default"]),
-          ],
+          args: ["--enable-gpu", "--use-angle=default"],
         },
       },
     },