A gate that stands in front of the suite delays the news it carries, so it runs beside it (#94)

The workflow ran everything in one job: check.sh, then build, then the e2e suite and the smokes.
The runner has two job slots and four cores, so the second slot lay idle for the whole run, and a
lint error was reported only after the full suite had passed in front of it - six minutes instead
of one.

Now `gate` and `suite` are two jobs without `needs:`. They start together, both have to pass.

The price is contention: while the gate runs, vitest and chromium share four cores, and the suite
measures text widths and frame counts, which a loaded machine reports differently. The gate
therefore caps vitest at two workers via GM_TEST_WORKERS, so two cores stay free for the browser
over the whole overlap. Locally the variable is unset and nothing changes.

Measured before the push: the cap costs vitest 4.4s (16.6s -> 21.0s), check.sh exits 0 with it,
build ok. Whether the split is worth it is a question for the runner - the expected net gain is
about 50s, and the acceptance is a measurement over at least two runs.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

.gitea/workflows/ci.yml

@@ -3,6 +3,15 @@
 # `runs-on: game-maker-ci` picks the image built from tools/ci/Dockerfile. The render device and
 # /dev/shm come from the runner's own container.options (/_stacks/git/runner/config.yaml), not
 # from here – without them chromium falls back to software WebGL.
+#
+# Two jobs without `needs:`, so they start together and use both slots of the runner
+# (`capacity: 2`, four cores). The gate no longer stands in front of the suite: a lint error used
+# to cost the full e2e run before it was reported, and the run reported it after six minutes
+# instead of one. Both still have to pass for the push to be green.
+#
+# The price is contention: while the gate runs, vitest and chromium share the four cores, and the
+# suite measures text widths and frame counts. That is why the gate caps vitest at two workers
+# (GM_TEST_WORKERS) – two cores stay free for the browser for the whole overlap.
 name: game-maker
 
 on:
@@ -10,6 +19,20 @@ on:
   workflow_dispatch:
 
 jobs:
+  gate:
+    runs-on: game-maker-ci
+    timeout-minutes: 20
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install
+        run: npm ci --no-audit --no-fund
+
+      - name: Gate
+        run: ./check.sh
+        env:
+          GM_TEST_WORKERS: 2
+
   suite:
     runs-on: game-maker-ci
     timeout-minutes: 45
@@ -25,9 +48,6 @@ jobs:
       - name: Install
         run: npm ci --no-audit --no-fund
 
-      - name: Gate
-        run: ./check.sh
-
       - name: Build
         run: npm run build