ci: publish famapp images to valhalla registry

Add Gitea Actions workflows (ci.yml, release.yml) that build and push
to registry.ginnoir.com. Disable GitHub release creation. Update all
doc/compose references from ghcr.io to registry.ginnoir.com.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

deploy/compose.example.yaml

@@ -20,7 +20,7 @@ volumes:
 
 services:
   famapp:
-    image: ${FAMAPP_IMAGE:-ghcr.io/ginnoir/famapp:latest}
+    image: ${FAMAPP_IMAGE:-registry.ginnoir.com/ginnoir/famapp:latest}
     pull_policy: ${FAMAPP_PULL_POLICY:-always}
     restart: unless-stopped
     environment: