perf: reduce CPU — Chromium GPU flags, healthcheck 30s to 120s, app card fixed height

- Chromium kiosk: add --disable-gpu-compositing, --disable-gpu-rasterization,
  --disable-software-rasterizer, --renderer-process-limit=1
  drops GPU process from 64% to 12% CPU
- Container healthchecks: 30s to 120s interval in first-boot and reconcile
- AppCard: min-height on description so cards dont shift

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

scripts/reconcile-containers.sh

@@ -156,7 +156,7 @@ build_run_cmd() {
 
   # Health check
   if [ -n "$SPEC_HEALTH_CMD" ]; then
-    cmd+=" --health-cmd=\"$SPEC_HEALTH_CMD\" --health-interval=30s --health-timeout=5s --health-retries=3"
+    cmd+=" --health-cmd=\"$SPEC_HEALTH_CMD\" --health-interval=120s --health-timeout=10s --health-retries=3"
   fi
 
   # Ports