fix(ci): increase E2E timeout to 10 min (was 5 min, too tight)

Sequential CI steps leave the runner under heavier load than the parallel
task check approach, so the E2E test can legitimately take 4-5 min.
Raise timeout 300→600 in integration_ui_test.sh and step timeout 6→12 min.
Job-level ceiling raised to 30 min to match.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.forgejo/workflows/ci.yml

@@ -9,7 +9,7 @@ jobs:
   check:
     name: Full Project Check
     runs-on: self-hosted
-    timeout-minutes: 20
+    timeout-minutes: 30
 
     steps:
       - uses: actions/checkout@v4
@@ -35,7 +35,7 @@ jobs:
         run: nix develop --command task integration
 
       - name: UI E2E tests
-        timeout-minutes: 6
+        timeout-minutes: 12
         run: nix develop --command task integration-ui
 
       - name: Coverage gate