feat: initialize warpbox.dev project structure and backend

Initialize the repository with the core Go backend architecture and a frontend mockup for warpbox.dev, a self-hosted file-sharing application.

- Set up Go backend modules for configuration, HTTP server, middleware, handlers, and templates.
- Add local development scripts, environment templates, and basic project configuration.
- Include a React-based frontend mockup under the docs directory.

backend/libs/helpers/human.go

@@ -0,0 +1,18 @@
+package helpers
+
+import "fmt"
+
+func FormatBytes(size int64) string {
+	const unit = 1024
+	if size < unit {
+		return fmt.Sprintf("%d B", size)
+	}
+
+	div, exp := int64(unit), 0
+	for n := size / unit; n >= unit; n /= unit {
+		div *= unit
+		exp++
+	}
+
+	return fmt.Sprintf("%.1f %ciB", float64(size)/float64(div), "KMGTPE"[exp])
+}

backend/libs/helpers/human_test.go

@@ -0,0 +1,19 @@
+package helpers
+
+import "testing"
+
+func TestFormatBytes(t *testing.T) {
+	tests := map[int64]string{
+		0:          "0 B",
+		512:        "512 B",
+		1024:       "1.0 KiB",
+		1536:       "1.5 KiB",
+		1073741824: "1.0 GiB",
+	}
+
+	for input, want := range tests {
+		if got := FormatBytes(input); got != want {
+			t.Fatalf("FormatBytes(%d) = %q, want %q", input, got, want)
+		}
+	}
+}

backend/libs/helpers/json.go

@@ -0,0 +1,20 @@
+package helpers
+
+import (
+	"encoding/json"
+	"net/http"
+)
+
+type ErrorResponse struct {
+	Error string `json:"error"`
+}
+
+func WriteJSON(w http.ResponseWriter, status int, payload any) {
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.WriteHeader(status)
+	_ = json.NewEncoder(w).Encode(payload)
+}
+
+func WriteJSONError(w http.ResponseWriter, status int, message string) {
+	WriteJSON(w, status, ErrorResponse{Error: message})
+}