readme update, minor style fixes

README.md

@@ -33,3 +33,28 @@ Practice Japanese Karaoke lyrics reading and typing at the same time with KaraDa
 * [ ] Correct lyrics timing inconsistencies (i.e. 网易云的歌词因为是业余用户上传的，时间戳不一定准确。但是 waveform 里面可以分析出每句歌词的具体开始结束时间，也许可以自动修正)
 
 
+## Development server
+
+### Requirements
+- Bun
+- Docker
+
+### 1. Environment setup
+1. Create your `.env` file by renaming `.env.example` to `.env`
+2. Add the following variable:
+   OPENROUTER_API_KEY=your_key_here
+   (Request the key from the repository owner)
+
+### 2. Start the database
+Run in the project root:
+docker compose up
+
+### 3. Install dependencies
+Install Bun:
+https://bun.com/get
+
+Then install project dependencies:
+bun install
+
+### 4. Start development server
+bun run dev