Device watchdog optimalization + pcap collection & tshark dissectors support + UI changes

Dockerfile.backend

@@ -3,6 +3,18 @@ FROM python:3.12-slim
 
 WORKDIR /app
 
+# tshark is used by PcapDecoder.get_packet_details() to decode previously
+# captured .pcap files (via `tshark -T json`) — the actual packet capture
+# itself happens remotely over SSH on each device, so no extra Linux
+# capabilities (NET_RAW/NET_ADMIN) are needed on this container, just the
+# tshark binary. DEBIAN_FRONTEND=noninteractive + the debconf preseed below
+# stop the wireshark-common postinst from prompting for the "allow
+# non-superusers to capture packets" question during the build.
+RUN apt-get update && \
+    echo "wireshark-common wireshark-common/install-setuid boolean false" | debconf-set-selections && \
+    DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends tshark && \
+    rm -rf /var/lib/apt/lists/*
+
 # Install dependencies first (layer caching)
 COPY requirements.txt .
 RUN pip install --no-cache-dir -r requirements.txt gunicorn
@@ -32,4 +44,4 @@ CMD gunicorn \
       --timeout 120 \
       --access-logfile - \
       --error-logfile - \
-      backend.app:app
+      backend.app:app