Add OpenCode initialization command to README (#101)

Co-authored-by: Viet Tran <viettranx@gmail.com>

Author: ergs0204

README.md

@@ -182,6 +182,7 @@ uipro init --ai qoder       # Qoder
 uipro init --ai roocode     # Roo Code
 uipro init --ai gemini      # Gemini CLI
 uipro init --ai trae        # Trae
+uipro init --ai opencode    # OpenCode
 uipro init --ai continue    # Continue (Skills)
 uipro init --ai all         # All assistants
 ```