Update Docker provider install instructions for pre-built container

Add separate instructions for:
- Pre-built container: docker run with display/volume flags
- Build from source: docker-compose run setup

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

README.md

@@ -483,24 +483,40 @@ docker-compose run --rm shell
 
 ### Installing AI Providers in Docker
 
-AI providers require browser-based authentication. Use the `setup` service which has display access:
+AI providers require browser-based authentication. You need display access for the browser to open.
+
+**Using the pre-built container:**
 
 ```bash
 # Allow Docker to access your display (Linux)
 xhost +local:docker
 
-# Start the setup container
+# Run with display access and persistent storage
+docker run -it --rm \
+  -e DISPLAY=$DISPLAY \
+  -v /tmp/.X11-unix:/tmp/.X11-unix \
+  -v smarttools-data:/root/.smarttools \
+  --network host \
+  gitea.brrd.tech/rob/smarttools bash
+
+# Inside the container:
+smarttools providers install
+```
+
+**Using docker-compose (build from source):**
+
+```bash
+xhost +local:docker
 docker-compose run --rm setup
 
-# Inside the container, use the interactive installer:
+# Inside the container:
 smarttools providers install
+```
 
-# Select a provider (1-5), it will:
-# - Install the CLI tool
-# - Open a browser for sign-in
-# - Configure the provider
+**After installing a provider:**
 
-# After signing in, test it:
+```bash
+# Test the provider works
 smarttools providers test claude
 ```