Rewrite README, build from compose, drop proxy network

- README: rewritten for this fork — build with docker compose, clone
  ComfyUI yourself as the mount, gfx1201 (RX 9700) confirmed working
- docker-compose.yml: add build: context, local image tag, ./ComfyUI
  volume, restore shm_size/render group/ipc, remove external
  proxy-network
- docker-run.sh: build locally, matching image tag and container name
- add .gitignore for the ComfyUI mount

docker-compose.yml

@@ -1,11 +1,18 @@
 services:
   comfyui:
+    # Built locally from the Dockerfile in this repo (docker compose build)
     image: comfyui-gfx1151:v0.8
     container_name: comfyui
-    # Shared memory allocation, should not be > than available RAM, feel free to lower it
-    #shm_size: 8G
+    build:
+      context: .
+    # Bump this in the Dockerfile (FROM rocm/pytorch:...) and here when updating
+    # Shared memory for PyTorch / ComfyUI internals.
+    # Must NOT be larger than available RAM. This is NOT VRAM.
+    shm_size: 8G
     volumes:
-      - /data/@sd/ComfyUI:/opt/ComfyUI
+      # Clone ComfyUI into this directory first (see README):
+      #   git clone https://github.com/comfyanonymous/ComfyUI
+      - ./ComfyUI:/opt/ComfyUI
     ports:
       - "8188:8188"
     environment:
@@ -15,14 +22,9 @@ services:
       - /dev/dri:/dev/dri
     group_add:
       - video
+      - render
     cap_add:
       - SYS_PTRACE
     security_opt:
       - seccomp:unconfined
-    networks:
-      - proxy-network
-
-networks:
-  proxy-network:
-    name: proxy-network
-    external: true
+    ipc: host