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]>

.gitignore

@@ -0,0 +1,27 @@
+# Python
+__pycache__/
+*.py[cod]
+*.egg-info/
+.venv/
+venv/
+
+# Editor
+.vscode/
+
+# Downloaded offline map tiles (large, regenerate via scripts/download_map_tiles.py
+# and deploy directly to the Pi - not tracked in git)
+static/vendor/tiles/
+
+# Runtime logs
+*.log
+
+# Local secrets (MAPTILER_KEY etc.) - never commit real credentials
+.env
+*.env
+!db/creds.env
+
+# Local SQLite trip-tracking databases (per-device data, not source)
+db/sql/
+
+# Imported dashcam footage (large, per-device data, not source)
+dash/videos/