Build the image on every deploy instead of pulling it

Portainer's "Pull and redeploy" tried to pull proposal-bot from Docker Hub
and failed. pull_policy: build skips the pull and rebuilds from the repo,
so code changes take effect on redeploy.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

compose.yaml

@@ -5,6 +5,8 @@ services:
     build:
       context: .
     image: proposal-bot:latest
+    # Always build from this repo on deploy; never try to pull proposal-bot from a registry.
+    pull_policy: build
     container_name: proposal-bot
     restart: unless-stopped
     # Reaps the headless Chromium processes the InDesign export starts.