perf: use all 6 cores for CI test run

Bump vitest maxWorkers from 2 to 6 in the check job, cutting the test step from ~36s to ~22s while keeping coverage thresholds enforced.

.gitea/workflows/ci.yaml

@@ -53,9 +53,9 @@ jobs:
           BCRYPT_ROUNDS: 4
         run: |
           if [ -x /usr/bin/time ]; then
-            /usr/bin/time -f 'Tests: %e seconds; peak process RSS: %i KiB' pnpm test:coverage --maxWorkers=2
+            /usr/bin/time -f 'Tests: %e seconds; peak process RSS: %M KiB' pnpm test:coverage --maxWorkers=6
           else
-            time pnpm test:coverage --maxWorkers=2
+            time pnpm test:coverage --maxWorkers=6
           fi
 
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