feat: add WannPassts booking app with Go backend and Vue frontend

Initial project setup for a privacy-focused, self-hosted scheduling app:

- Go backend with JWT auth, SQLite storage, and chi router
- Calendar integrations via Google OAuth (FreeBusy), CalDAV, and ICS links
- Public booking pages with configurable slots and booking requests
- AES-256-GCM encryption for stored provider tokens
- Vue 3 + TypeScript frontend with Vite, Pinia, and Vue Router
- Docs, .gitignore, and .env.example for local development

backend/cmd/server/main.go

@@ -0,0 +1,30 @@
+package main
+
+import (
+	"log"
+	"net/http"
+
+	"wannpassts/internal/calendar"
+	"wannpassts/internal/config"
+	"wannpassts/internal/db"
+	"wannpassts/internal/httpapi"
+)
+
+func main() {
+	cfg := config.Load()
+
+	database, err := db.Open(cfg.DBPath)
+	if err != nil {
+		log.Fatalf("Datenbank konnte nicht geöffnet werden: %v", err)
+	}
+	defer database.Close()
+
+	syncer := &calendar.Syncer{DB: database, Cfg: &cfg}
+	srv := httpapi.New(database, &cfg, syncer)
+
+	addr := ":" + cfg.Port
+	log.Printf("WannPassts Backend läuft auf http://localhost%s", addr)
+	if err := http.ListenAndServe(addr, srv.Router()); err != nil {
+		log.Fatal(err)
+	}
+}