Update README with optional OpenCode installation instructions

Author: chenjingxiong

README.md

@@ -102,12 +102,28 @@ GOOGLE_API_KEY=your_google_key
 
 ## 🚀 First-time Setup
 
-After starting the container, run inside the VSCode terminal:
+After starting the container, open the VSCode terminal (`` Ctrl+` ``):
+
+### Required Setup
+
+```bash
+# Authenticate Claude Code (first run will prompt for login)
+claude
+```
+
+### Optional: Install OpenCode & Sisyphus
+
+OpenCode and Oh My OpenCode (Sisyphus) can be installed if needed:
 
 ```bash
-# Complete OpenCode/Sisyphus installation
+# Install OpenCode CLI
+curl -fsSL https://opencode.ai/install.sh | bash
+
+# Install Oh My OpenCode
 bunx oh-my-opencode install
 
-# Authenticate Claude Code
-claude
+# Authenticate AI models
+opencode auth list
 ```
+
+> **Note**: OpenCode/Sisyphus installation is optional and requires interactive setup.