ci(desktop): publish test reports when the desktop job fails

build-desktop runs five test suites (:quartz:jvmTest, :commons:jvmTest,
:nestsClient:jvmTest, :cli:test, :desktopApp:test) across three OSes and
was the only test-running job with no failure reporting — test-geode,
test-quartz-ios and test-and-build-android all upload on failure.

When a test failed there, the console printed the test name and the
exception class and nothing else, and the reports died with the runner.
Run 10540's macOS leg is the case in point:

  NostrClientNegentropySyncTest[jvm] >
    multiRoundReconcileStreamsEveryEventThrough[jvm] FAILED
      com.vitorpamplona.quartz...NegentropySyncException at
      NostrClientNegentropySyncTest.kt:146

Line 146 is the runBlocking frame, so all that survives is "something
threw". NegentropySyncException carries a `detail` naming which of the
four branches fired — connect timeout, idle silence mid-reconcile,
NEG-ERR, or disconnect — and that string is what says whether the run
hit a real protocol fault or lost a race against a loaded runner. It
was unrecoverable.

Two steps, mirroring the Android job: the same pinned
mikepenz/action-junit-report annotates the failing assertion inline
(annotate_only keeps this working under `permissions: contents: read`
and on fork PRs), and the HTML reports upload on failure for the full
stack traces the annotations truncate. Artifacts are named per-OS
because the three matrix legs share a run.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017shnUK5t71BkBXgTAcACbA

.github/workflows/build.yml

@@ -94,6 +94,39 @@ jobs:
             $CMD
           fi
 
+      # This job runs five test suites (:quartz, :commons, :nestsClient, :cli,
+      # :desktopApp) but, unlike test-geode / test-quartz-ios /
+      # test-and-build-android, published nothing when one of them failed. The
+      # console line names the failing test and the exception class and stops
+      # there, so the message is lost with the runner. That is how the
+      # NostrClientNegentropySyncTest failure in run 10540 became
+      # undiagnosable: NegentropySyncException carries a `detail` naming which
+      # branch fired (connect timeout / idle silence / NEG-ERR / disconnect),
+      # and nobody could read it. Same action and pin as the Android job below.
+      - name: Desktop Test Report
+        uses: mikepenz/action-junit-report@d9f48fc87bc235f7e214acf696ca5abc0a986f16 # v6.4.2
+        if: always()
+        with:
+          report_paths: '**/build/test-results/**/TEST-*.xml'
+          annotate_only: true
+          detailed_summary: true
+          fail_on_failure: true
+
+      # The HTML reports carry the full stack traces and stdout/stderr the
+      # annotations truncate. Named per-OS because the three matrix legs upload
+      # into the same run and artifact names must be unique.
+      - name: Upload Desktop Test Reports
+        uses: actions/upload-artifact@v7
+        if: failure()
+        with:
+          name: Desktop Test Reports (${{ matrix.os }})
+          path: |
+            quartz/build/reports/tests
+            commons/build/reports/tests
+            nestsClient/build/reports/tests
+            cli/build/reports/tests
+            desktopApp/build/reports/tests
+
       # jpackage pins libicu to the build host's version (libicu74 on
       # ubuntu-24.04). Rewrite the .deb so testers on other Debian/Ubuntu
       # releases can install the uploaded artifact.