ci: make API 37 preview emulator boot fail-fast and diagnosable

The custom-provisioned preview job hung in 'Boot emulator and run E2E' until
the 35-min cap: adb wait-for-device had no timeout and the emulator's own
output was never captured, so a failed boot was both invisible and unbounded.
Bound the wait with a single 300s timeout covering device registration + full
boot, retry once, capture the emulator log, and dump it (plus logcat) on
failure.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -227,13 +227,42 @@ jobs:
       - name: Boot emulator and run E2E
         run: |
           set -euo pipefail
-          "$ANDROID_SDK_ROOT/emulator/emulator" -avd api37 \
-            -no-window -gpu swiftshader_indirect -noaudio -no-boot-anim -no-snapshot -camera-back none &
-          adb wait-for-device
-          timeout 300 bash -c 'while [ "$(adb shell getprop sys.boot_completed | tr -d "\r")" != "1" ]; do sleep 3; done'
+          EMU_LOG="${RUNNER_TEMP:-/tmp}/emulator.log"
+
+          boot_emulator() {
+            echo "::group::Start API 37 emulator (attempt $1)"
+            # Capture the emulator's own output — without this a boot failure is invisible.
+            "$ANDROID_SDK_ROOT/emulator/emulator" -avd api37 \
+              -no-window -no-audio -no-boot-anim -no-snapshot -accel on \
+              -gpu swiftshader_indirect -camera-back none -camera-front none > "$EMU_LOG" 2>&1 &
+            # ONE bounded wait covering both device registration and full boot, so a stuck emulator
+            # fails fast instead of hanging the whole job until the 35-min cap (the original bug).
+            if timeout 300 adb wait-for-device shell \
+                'while [ "$(getprop sys.boot_completed | tr -d "\r")" != "1" ]; do sleep 2; done'; then
+              echo "::endgroup::"; return 0
+            fi
+            echo "::endgroup::"
+            echo "::warning::API 37 emulator did not boot within 300s (attempt $1)"
+            adb devices || true
+            echo "--- emulator.log (tail) ---"; tail -120 "$EMU_LOG" || true
+            adb emu kill 2>/dev/null || true
+            sleep 5
+            return 1
+          }
+
+          booted=0
+          for attempt in 1 2; do boot_emulator "$attempt" && { booted=1; break; }; done
+          [ "$booted" = "1" ] || { echo "::error::API 37 preview emulator failed to boot after 2 attempts"; exit 1; }
+
           adb shell input keyevent 82 || true
           ./gradlew connectedDebugAndroidTest --stacktrace
 
+      - name: Dump emulator log on failure
+        if: failure()
+        run: |
+          echo "--- emulator.log ---"; tail -200 "${RUNNER_TEMP:-/tmp}/emulator.log" 2>/dev/null || echo "(none)"
+          echo "--- logcat ---"; adb logcat -d 2>/dev/null | tail -120 || echo "(device unavailable)"
+
       - name: Shut down emulator
         if: always()
         run: adb emu kill || true