Revive yaris-obd: USB OBD adapter, real GPS/GNSS, offline map, hotspot, SQLite logging, dashcam retrieval

Squashed rewrite of the project revival work (replaces prior history on this
branch to remove personal data that had been accidentally committed - real
LAN IP, GPS coordinates, home WiFi SSID, and phone model). See PLAN.md for
full phase-by-phase details. Summary:

- Phase 2: adapt app_obd.py for a USB OBD-II adapter (was Bluetooth-only),
  auto-detect /dev/ttyUSB*, fix several pre-existing crash bugs.
- Phase 3/4: make the web UI work fully offline (vendored Socket.IO/Leaflet/
  Chart.js/FontAwesome, offline map tile downloader script, live GPS marker
  tracking fix).
- Phase 5: systemd deployment/autostart on the Pi.
- Phase 6: WiFi hotspot mode via NetworkManager (auto-switch between home
  WiFi and a local AP for in-car web UI access), mDNS hostname + port 80
  redirect so the UI is reachable at a plain hostname with no port number.
- Phase 7: fix app_db.py/app_sql.py bugs, wire up local SQLite trip logging.
- Phase 8: brand-agnostic USB dashcam file retrieval (lsblk transport-based
  detection, works with any dashcam brand/folder layout).
- Rewritten readme.md with a proper project overview.

Co-authored-by: Copilot <[email protected]>

deploy/yaris-netwatch.sh

@@ -0,0 +1,47 @@
+#!/bin/bash
+# yaris-netwatch.sh
+#
+# Runs periodically via yaris-netwatch.timer. If wlan0 is currently in
+# AP/hotspot mode, briefly attempts to reconnect to the known home WiFi.
+# If that succeeds, we're back on home WiFi (used for syncing itinerary/
+# dashcam data to the remote server). If it fails (still out of range),
+# reactivates the hotspot so the web UI stays reachable locally in the car.
+#
+# The Pi's onboard WiFi radio (BCM43438) cannot act as an AP and scan for
+# client networks at the same time, so this brief switch-and-check is the
+# only way to detect "home WiFi is back in range" while sitting in AP mode.
+# The reverse direction (home WiFi -> hotspot, i.e. leaving range) is handled
+# automatically by NetworkManager's own autoconnect-priority mechanism and
+# needs no watcher: the "home-wifi" profile has a higher
+# connection.autoconnect-priority than Hotspot, so NM tries it first whenever
+# the device needs to reconnect, and falls through to Hotspot on its own once
+# home WiFi drops out of range.
+
+set -u
+
+LOG_TAG="yaris-netwatch"
+HOME_CON="home-wifi"
+AP_CON="Hotspot"
+IFACE="wlan0"
+LAST_LOG="/tmp/yaris-netwatch-last.log"
+
+active_con() {
+    nmcli -t -f DEVICE,CONNECTION device status | awk -F: -v d="$IFACE" '$1==d {print $2}'
+}
+
+current="$(active_con)"
+
+if [ "$current" != "$AP_CON" ]; then
+    # Already on home WiFi (or something else) - nothing to do.
+    logger -t "$LOG_TAG" "wlan0 is on '$current', no action needed"
+    exit 0
+fi
+
+logger -t "$LOG_TAG" "wlan0 is on hotspot, checking for home WiFi ($HOME_CON)..."
+
+if nmcli --wait 20 con up "$HOME_CON" >"$LAST_LOG" 2>&1; then
+    logger -t "$LOG_TAG" "home WiFi found, switched to '$HOME_CON'"
+else
+    logger -t "$LOG_TAG" "home WiFi not found, restoring hotspot"
+    nmcli con up "$AP_CON" >>"$LAST_LOG" 2>&1
+fi