perf(ci): decouple e2e from frontend — build frontend inline in e2e job

Before: e2e \`needs: [frontend]\` waited for the frontend job to upload
a build artifact, then downloaded it. With multiple runners this means
the third runner sat idle for ~6 min while frontend ran, then started
e2e — total wall-clock max(backend, frontend+e2e) ≈ 11 min.

After: e2e builds its own frontend (npm ci + npm run build are already
in the job; just dropped the artifact download step and added the
build). e2e starts immediately on a free runner. Adds ~1-2 min to the
e2e job duration but removes ~5 min of waiting and eliminates the
cross-job artifact mechanism entirely.

Side benefit: no more \`actions/upload-artifact\` v3/v4 GHES headaches
on the cross-job handoff. The \`if: always()\` upload of the
playwright-report at the end of e2e is kept (failure report retrieval
is still useful), but it's a leaf-output, not a dependency.

Net wall-clock: max(backend=9m, frontend=6m, e2e=7m) ≈ 9 min on the
3-runner setup, down from ~11 min.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.gitea/workflows/ci.yml

@@ -125,15 +125,14 @@ jobs:
       - name: Build
         run: cd frontend && NODE_OPTIONS="--max-old-space-size=4096" npm run build
 
-      - name: Upload build artifact
-        uses: actions/upload-artifact@v3
-        with:
-          name: frontend-dist
-          path: frontend/dist
-          retention-days: 1
+      # Build artifact intentionally NOT uploaded. The e2e job below builds
+      # its own frontend rather than downloading one from this job, so there
+      # is no need for the cross-job artifact handoff (which previously broke
+      # on actions/upload-artifact@v4 GHES support and forced a v3 pin).
+      # Decoupling also lets e2e start immediately rather than waiting for
+      # this job to finish — important on a multi-runner setup.
 
   e2e:
-    needs: [frontend]
     runs-on: ubuntu-latest
 
     services:
@@ -188,11 +187,13 @@ jobs:
       - name: Install frontend dependencies
         run: cd frontend && npm ci
 
-      - name: Download frontend build
-        uses: actions/download-artifact@v3
-        with:
-          name: frontend-dist
-          path: frontend/dist
+      - name: Build frontend
+        # Building inline (instead of downloading an artifact from the
+        # frontend job) drops the cross-job dependency, so e2e can start
+        # immediately on a free runner. Adds ~1-2 min of build time, but
+        # eliminates the artifact-upload mechanism entirely (no more
+        # v3/v4 GHES headaches) and saves ~5 min of waiting.
+        run: cd frontend && NODE_OPTIONS="--max-old-space-size=4096" npm run build
 
       - name: Install Playwright browser
         run: cd frontend && npx playwright install --with-deps chromium