chore: initial commit of foundryvtt-admin

Spun out of the hbm-books working folder into its own repo. A small
backend+frontend+COBOL admin tool for managing Foundry VTT worlds
(socket inspection, join/shutdown debugging).

docker-compose.yml

@@ -0,0 +1,29 @@
+services:
+  backend:
+    build: ./backend
+    ports:
+      - "30001:3000"
+    env_file: .env.backend
+    volumes:
+      - shared-data:/app/shared
+    extra_hosts:
+      - "host.docker.internal:host-gateway"
+
+  frontend:
+    build: ./frontend
+    ports:
+      - "30002:5173"
+    environment:
+      - VITE_BACKEND_URL=http://localhost:30001
+
+  cobol:
+    build: ./cobol
+    tty: true
+    stdin_open: true
+    volumes:
+      - shared-data:/app/shared
+    depends_on:
+      - backend
+
+volumes:
+  shared-data: