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

svelte.config.js

@@ -1,17 +1,13 @@
-import adapter from '@sveltejs/adapter-auto';
+import adapter from '@sveltejs/adapter-node';
 
 /** @type {import('@sveltejs/kit').Config} */
 const config = {
 	compilerOptions: {
-		// Force runes mode for the project, except for libraries. Can be removed in svelte 6.
 		runes: ({ filename }) => (filename.split(/[/\\]/).includes('node_modules') ? undefined : true)
 	},
 	kit: {
-		// adapter-auto only supports some environments, see https://svelte.dev/docs/kit/adapter-auto for a list.
-		// If your environment is not supported, or you settled on a specific environment, switch out the adapter.
-		// See https://svelte.dev/docs/kit/adapters for more information about adapters.
 		adapter: adapter()
 	}
 };
 
-export default config;
+export default config;