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]>

modules/app_db.py

@@ -2,22 +2,30 @@ from pymongo import MongoClient
 from dotenv import load_dotenv
 import os
 
-load_dotenv("../db/creds.env")
+# Load creds.env from the repo's db/ folder regardless of the process's cwd.
+_BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+load_dotenv(os.path.join(_BASE_DIR, "db", "creds.env"))
 
-mUser = os.getenv()
-mPass = os.getenv()
-mDB = os.getenv()
+mUser = os.getenv("mangosrv_user")
+mPass = os.getenv("mangosrv_pass")
+mDB = os.getenv("mangosrv_db")
 
 def get_database():
- 
-   # Provide the mongodb atlas url to connect python to mongodb using pymongo
-   CONNECTION_STRING = "mongodb+srv://"+ mUser + ":" + mPass + "@cluster.mongodb.net/" + mDB
- 
-   # Create a connection using MongoClient. You can import MongoClient or use pymongo.MongoClient
-   client = MongoClient(CONNECTION_STRING)
-  
+    if not mUser or not mPass or not mDB:
+        raise RuntimeError(
+            "MongoDB credentials are missing. Set mangosrv_user, mangosrv_pass, "
+            "and mangosrv_db in db/creds.env."
+        )
+
+    # Provide the mongodb atlas url to connect python to mongodb using pymongo
+    CONNECTION_STRING = "mongodb+srv://" + mUser + ":" + mPass + "@cluster.mongodb.net/" + mDB
+
+    # Create a connection using MongoClient. You can import MongoClient or use pymongo.MongoClient
+    client = MongoClient(CONNECTION_STRING)
+    return client[mDB]
+
 # This is added so that many files can reuse the function get_database()
-if __name__ == "__main__":   
-  
-   # Get the database
-   dbname = get_database()
+if __name__ == "__main__":
+
+    # Get the database
+    dbname = get_database()