fix: restore local build in docker compose for local code deployment (#9)

docker-compose.yml referenced only the Gitea registry image, so
`docker compose up --build` ignored local source and never shipped
the channel variant grouping feature. Add a build section (root
context, local Dockerfile) alongside the registry image tag so
compose builds local code while keeping the published image name.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docker-compose.yml

@@ -1,5 +1,8 @@
 services:
   nodecast-tv:
+    build:
+      context: .
+      dockerfile: Dockerfile
     image: gitea.anthonybouteiller.ovh/blomios/nodecast-tv:latest
     container_name: nodecast-tv
     ports: