Initial commit: OpenCode Zen Proxy

Proxy translating OpenAI/Anthropic Messages API to OpenCode Zen's free models.
Pure stdlib Go 1.22, no external dependencies.

- OpenAI Chat Completions (/v1/chat/completions) with streaming
- Anthropic Messages API (/v1/messages) with streaming
- Model aliases for 5 free models
- Auth middleware support
- Session rotation (30min per user key)

main.go

@@ -0,0 +1,55 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+
+	"opencode-proxy/internal/proxy"
+	"opencode-proxy/internal/server"
+)
+
+const appVersion = "1.0.0"
+
+func main() {
+	port := flag.String("port", "", "Server port (default: 6446)")
+	host := flag.String("host", "", "Server host (default: 127.0.0.1)")
+	apiKey := flag.String("api-key", "", "API key to protect the proxy (optional, can also be set via OPENCODE_PROXY_KEY env var)")
+	showVersion := flag.Bool("version", false, "Show version and exit")
+	flag.Parse()
+
+	if *showVersion {
+		fmt.Printf("opencode-proxy v%s\n", appVersion)
+		return
+	}
+
+	// Resolve API key: flag takes precedence, then env var
+	key := *apiKey
+	if key == "" {
+		key = os.Getenv("OPENCODE_PROXY_KEY")
+	}
+
+	p := proxy.NewProxy(key)
+	srv := server.NewServer(p)
+
+	if *port != "" {
+		srv.SetPort(*port)
+	}
+	if *host != "" {
+		srv.SetHost(*host)
+	}
+
+	fmt.Printf("OpenCode Zen Proxy v%s\n", appVersion)
+	fmt.Printf("Starting on %s:%s\n", srv.Host(), srv.Port())
+	if key != "" {
+		fmt.Println("API key protection: ENABLED")
+	} else {
+		fmt.Println("API key protection: DISABLED (no key set)")
+	}
+	fmt.Printf("Free models available: %d\n", len(p.Models()))
+
+	if err := srv.Start(); err != nil {
+		fmt.Fprintf(os.Stderr, "Server error: %v\n", err)
+		os.Exit(1)
+	}
+}