docs: update deployment instructions with all three methods (.env file, docker run env vars, docker-compose)

Dockerfile

@@ -1,7 +1,18 @@
 FROM node:18-alpine
+
 WORKDIR /app
+
+# Copy package files first for better layer caching
 COPY package*.json ./
+
+# Install dependencies (including dotenv)
 RUN npm install
+
+# Copy application source code
 COPY . .
-RUN npm prune --production
-CMD ["node", "index.js"]
+
+# Expose port if needed (optional, Matrix uses websocket)
+# EXPOSE 3000
+
+# Run the bot (dotenv will auto-load from /app/.env or environment variables)
+CMD ["node", "index.js"]