feat: build Go-based SearXNG-compatible search service

Implement an API-first Go rewrite with local engine adapters, upstream fallback, and Nix-based tooling so searches can run without matching the original UI while preserving response compatibility.

Made-with: Cursor

cmd/searxng-go/main.go

@@ -0,0 +1,43 @@
+package main
+
+import (
+	"log"
+	"net/http"
+	"os"
+	"time"
+
+	"github.com/ashie/gosearch/internal/httpapi"
+	"github.com/ashie/gosearch/internal/search"
+)
+
+func main() {
+	port := os.Getenv("PORT")
+	if port == "" {
+		port = "8080"
+	}
+
+	upstreamURL := os.Getenv("UPSTREAM_SEARXNG_URL")
+
+	timeout := 10 * time.Second
+	if v := os.Getenv("HTTP_TIMEOUT"); v != "" {
+		if d, err := time.ParseDuration(v); err == nil {
+			timeout = d
+		}
+	}
+
+	svc := search.NewService(search.ServiceConfig{
+		UpstreamURL: upstreamURL,
+		HTTPTimeout: timeout,
+	})
+
+	h := httpapi.NewHandler(svc)
+
+	mux := http.NewServeMux()
+	mux.HandleFunc("/healthz", h.Healthz)
+	mux.HandleFunc("/search", h.Search)
+
+	addr := ":" + port
+	log.Printf("searxng-go listening on %s", addr)
+	log.Fatal(http.ListenAndServe(addr, mux))
+}
+