Let the extension update itself, and host the dashboard

Chrome has no update channel for an unpacked extension, so every pull left one
manual step: click reload on its card. The dashboard now publishes the version
its own checkout ships at /api/autobuyer/status, and the extension reloads
itself when it is behind — chrome.runtime.reload() re-reads the folder from
disk, which the update check has already pulled into. It only ever runs code
that is on disk, so a reload that changes nothing is reported and waited out
rather than repeated; a dashboard that is behind is ignored.

Also adds the deploy stack for running the dashboard on the droplet, next to
the autotrader one: it joins that nginx's network and renders a server block
into its conf.d rather than standing up a second ingress. AUTOFIRMER_DB moves
the SQLite file onto a volume, since the working directory in a container is
replaced on every deploy.

And waitFor gained `hidden`: an absent gate matched on DOM presence only, so a
modal that closes by going display:none could never satisfy it. The extension
grew a visibility probe for this — locate cannot answer it, because absent and
hidden are both errors there and a wait gate has to tell them apart.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

deploy/docker-compose.yml

@@ -0,0 +1,30 @@
+# The dashboard, alongside the autotrader stack rather than instead of it: the
+# droplet already runs one nginx on 80/443, and this joins that network so the
+# same ingress can proxy to it. Nothing here publishes a host port.
+name: autofirmer
+
+services:
+  autofirmer:
+    build:
+      context: ..
+      dockerfile: Dockerfile
+    image: autofirmer:local
+    container_name: autofirmer
+    restart: unless-stopped
+    environment:
+      AUTOFIRMER_DB: /data/autotrader.sqlite
+    volumes:
+      - autofirmer-data:/data
+    expose:
+      - "3000"
+    networks: [web]
+
+networks:
+  # Created by the autotrader stack. `external` so this compose file never tries
+  # to own it — bringing this stack down must not take the ingress with it.
+  web:
+    name: ${SHARED_NETWORK:-autotrader-vps_web}
+    external: true
+
+volumes:
+  autofirmer-data: