Initial commit: boarding pass to AirTrail pipeline

Photograph/screenshot a boarding pass, decode its BCBP barcode (PDF417/
Aztec/QR/DataMatrix), fetch the historical flight track from FlightAware
the day after the flight, stage it for review, and write it into AirTrail
via its REST API on approval. ntfy notifications carry signed
Approve/Deny/Investigate actions.

docker-compose.yml

@@ -0,0 +1,18 @@
+services:
+  boarding-pass:
+    build: .
+    container_name: boarding-pass
+    restart: unless-stopped
+    env_file: .env
+    environment:
+      TZ: ${TZ:-Etc/UTC}
+    volumes:
+      - ./instance:/app/instance
+    # No host port published by default - reach this via NPMplus on the
+    # shared proxy network (see README for the network + bypass config).
+    networks:
+      - proxy
+
+networks:
+  proxy:
+    external: true