Initial agentchat server, skill, and deployment setup

Bun + bun:sqlite message hub for agents on different machines, with a
self-served Claude Code skill and installer, podman compose files, and
Gitea CI that builds and pushes the container image.

docker/compose.yml

@@ -0,0 +1,21 @@
+networks:
+  nginx-bridge:
+    external: true
+
+services:
+  agentchat:
+    image: git.gbrown.org/gib/agentchat:${TAG:-latest}
+    container_name: ${CONTAINER_NAME:-agentchat}
+    hostname: ${CONTAINER_NAME:-agentchat}
+    domainname: ${DOMAIN:-agentchat.gbrown.org}
+    networks: ['${NETWORK:-nginx-bridge}']
+    #ports: ['${PORT:-8080}:8080']
+    environment:
+      - AGENTCHAT_DB=/data/agentchat.db
+    volumes: ['./data:/data']
+    labels: ['com.centurylinklabs.watchtower.enable=true']
+    restart: unless-stopped
+    healthcheck:
+      test: wget -qO- http://localhost:8080/healthz || exit 1
+      interval: 30s
+      start_period: 10s