initialize backend project

Signed-off-by: Tobias Erbshäußer <tobias@tesoft.dev>

backend/.gitignore

@@ -0,0 +1 @@
+.idea

backend/api.go

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+package main
+
+import "net/http"
+
+type ApiHandler struct {
+}
+
+func NewApiHandler() *ApiHandler {
+	// TODO
+	return &ApiHandler{}
+}
+
+func (api *ApiHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	// TODO
+}

backend/backend.iml

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+<?xml version="1.0" encoding="UTF-8"?>
+<module type="WEB_MODULE" version="4">
+  <component name="Go" enabled="true" />
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>

backend/go.mod

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+module backend
+
+go 1.25

backend/main.go

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+package main
+
+import (
+	"log"
+	"net/http"
+	"os"
+)
+
+func main() {
+	port := os.Getenv("PORT")
+	if port == "" {
+		port = "8080"
+	}
+
+	staticFolder := os.Getenv("STATIC_FOLDER")
+	if staticFolder == "" {
+		staticFolder = "static"
+	}
+
+	fsHandler := http.FileServer(http.Dir(staticFolder))
+	apiHandler := NewApiHandler()
+
+	mux := http.NewServeMux()
+	mux.Handle("/", fsHandler)
+	mux.Handle("/api/", apiHandler)
+
+	log.Println("Listening on port", port)
+	err := http.ListenAndServe(":"+port, mux)
+	if err != nil {
+		log.Fatalln(err.Error())
+	}
+}