feat: extract into remaining packages

There has been a cyclic dependency.
transaction
	-> treasure_chest
	-> transaction_recurring
	-> transaction

This has been temporarily solved by moving the GenerateTransactions
function into the transaction package. In the future, this function has
to be rewritten to use a proper Service insteas of direct DB access or
replaced with a different system entirely.

internal/core/http.go

@@ -0,0 +1,42 @@
+package core
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"net/http"
+	"strings"
+	"time"
+)
+
+func TriggerToast(ctx context.Context, w http.ResponseWriter, r *http.Request, class string, message string) {
+	if IsHtmx(r) {
+		w.Header().Set("Hx-Trigger", fmt.Sprintf(`{"toast": "%v|%v"}`, class, strings.ReplaceAll(message, `"`, `\"`)))
+	} else {
+		slog.ErrorContext(ctx, "Trying to trigger toast in non-HTMX request")
+	}
+}
+
+func TriggerToastWithStatus(ctx context.Context, w http.ResponseWriter, r *http.Request, class string, message string, statusCode int) {
+	TriggerToast(ctx, w, r, class, message)
+	w.WriteHeader(statusCode)
+}
+
+func DoRedirect(w http.ResponseWriter, r *http.Request, url string) {
+	if IsHtmx(r) {
+		w.Header().Add("Hx-Redirect", url)
+	} else {
+		http.Redirect(w, r, url, http.StatusSeeOther)
+	}
+}
+
+func WaitMinimumTime[T any](waitTime time.Duration, f func() (T, error)) (T, error) {
+	start := time.Now()
+	result, err := f()
+	time.Sleep(waitTime - time.Since(start))
+	return result, err
+}
+
+func IsHtmx(r *http.Request) bool {
+	return r.Header.Get("Hx-Request") == "true"
+}