Fix NAS stats returning zeros instead of real download numbers

Two independent bugs, either of which made gather_castopod() report
total_downloads: 0 on a dev machine — indistinguishable from a podcast nobody
listens to.

- NAS_SSH hardcoded mmgnas-10g, which is only reachable when the 10G cable is
  physically connected. Now probed once per process with a 2s timeout and
  falls back to mmgnas; NAS_HOST overrides detection entirely. Same detection
  added to deploy_stats_cron.sh.
- _run_db_query treated any docker binary on PATH as "running on the NAS", so
  a machine with Docker Desktop queried its own daemon, found no castopod
  container, and never fell back to SSH. Only the QNAP container-station path
  counts now.

Real figures with both fixed: 3803 downloads, 750 unique listeners.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

deploy_stats_cron.sh

@@ -5,9 +5,21 @@
 
 set -e
 
-NAS_HOST="mmgnas-10g"
 NAS_USER="luke"
 NAS_PORT="8001"
+
+# mmgnas-10g is only up when the 10G cable is physically connected. Prefer it
+# when reachable (faster transfers), otherwise fall back to the wireless/1G
+# host. Override with NAS_HOST=... to skip detection.
+if [ -z "$NAS_HOST" ]; then
+    if ssh -p "$NAS_PORT" -o ConnectTimeout=2 -o BatchMode=yes \
+           "$NAS_USER@mmgnas-10g" true 2>/dev/null; then
+        NAS_HOST="mmgnas-10g"
+    else
+        NAS_HOST="mmgnas"
+    fi
+    echo "NAS host: $NAS_HOST"
+fi
 DOCKER_BIN="/share/CACHEDEV1_DATA/.qpkg/container-station/bin/docker"
 DEPLOY_DIR="/share/CACHEDEV1_DATA/podcast-stats"
 CONTAINER_NAME="podcast-stats"