feat: containerize with Docker Compose + Ollama

Add full Docker setup so the app runs with a single 'docker compose up':

- Dockerfile: multi-stage build (node:22-alpine) for the SvelteKit app
- docker-compose.yml: three services:
  1. ollama: runs Ollama server with persistent volume for models
  2. model-init: one-shot container that pulls the configured model
     after Ollama is healthy, then exits
  3. app: the SvelteKit app, starts only after model-init succeeds
- .env.docker: set OLLAMA_MODEL to control which model is pulled
- .dockerignore: keeps image lean
- Switched adapter-auto to adapter-node (required for Docker/Node hosting)
- Updated README with Docker and local dev instructions

Usage:
  docker compose up              # default: llama3
  OLLAMA_MODEL=gemma2 docker compose up  # any Ollama model

docker-compose.yml

@@ -0,0 +1,48 @@
+services:
+  ollama:
+    image: ollama/ollama:latest
+    container_name: english-styler-ollama
+    ports:
+      - "11434:11434"
+    volumes:
+      - ollama-data:/root/.ollama
+    healthcheck:
+      test: ["CMD", "ollama", "list"]
+      interval: 5s
+      timeout: 3s
+      retries: 30
+      start_period: 5s
+    restart: unless-stopped
+
+  model-init:
+    image: ollama/ollama:latest
+    container_name: english-styler-model-init
+    depends_on:
+      ollama:
+        condition: service_healthy
+    environment:
+      OLLAMA_HOST: http://ollama:11434
+    entrypoint: >
+      sh -c "
+        echo 'Pulling Ollama model: ${OLLAMA_MODEL:-llama3}' &&
+        ollama pull ${OLLAMA_MODEL:-llama3} &&
+        echo 'Model ready ✅'
+      "
+    restart: "no"
+
+  app:
+    build: .
+    container_name: english-styler-app
+    ports:
+      - "3000:3000"
+    depends_on:
+      model-init:
+        condition: service_completed_successfully
+    environment:
+      OPENAI_BASE_URL: http://ollama:11434/v1
+      OPENAI_API_KEY: ollama
+      OPENAI_MODEL: ${OLLAMA_MODEL:-llama3}
+    restart: unless-stopped
+
+volumes:
+  ollama-data: