feat: v9.8.1 pre-built Docker images and GHCR release workflow

Setup.py now asks whether to pull pre-built images from GHCR
(recommended) or build from source. Pre-built mode skips the
15-minute compile step entirely.

- Add .github/workflows/release.yml (builds+pushes 4 images on tag)
- Add docker-compose.build.yml (source-build overlay)
- Switch docker-compose.prod.yml from build: to image: refs
- Add --build-mode CLI arg and wizard step to setup.py
- Bump version to 9.8.1 across all files
- Document TOD_VERSION env var in CONFIGURATION.md

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docker-compose.build.yml

@@ -0,0 +1,28 @@
+# docker-compose.build.yml -- Build-from-source override
+#
+# Adds build contexts so Docker Compose builds images locally instead of
+# pulling pre-built images from GHCR.
+#
+# Usage:
+#   docker compose -f docker-compose.yml -f docker-compose.prod.yml \
+#     -f docker-compose.build.yml --env-file .env.prod up -d --build
+
+services:
+  api:
+    build:
+      context: .
+      dockerfile: infrastructure/docker/Dockerfile.api
+
+  poller:
+    build:
+      context: ./poller
+      dockerfile: ./Dockerfile
+
+  frontend:
+    build:
+      context: .
+      dockerfile: infrastructure/docker/Dockerfile.frontend
+
+  winbox-worker:
+    build:
+      context: ./winbox-worker