Move internal packages to an internal folder

For reference: https://go.dev/doc/go1.4#internalpackages

internal/ui/category_edit.go

@@ -0,0 +1,54 @@
+// SPDX-FileCopyrightText: Copyright The Miniflux Authors. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package ui // import "miniflux.app/v2/internal/ui"
+
+import (
+	"net/http"
+
+	"miniflux.app/v2/internal/http/request"
+	"miniflux.app/v2/internal/http/response/html"
+	"miniflux.app/v2/internal/ui/form"
+	"miniflux.app/v2/internal/ui/session"
+	"miniflux.app/v2/internal/ui/view"
+)
+
+func (h *handler) showEditCategoryPage(w http.ResponseWriter, r *http.Request) {
+	sess := session.New(h.store, request.SessionID(r))
+	view := view.New(h.tpl, r, sess)
+
+	user, err := h.store.UserByID(request.UserID(r))
+	if err != nil {
+		html.ServerError(w, r, err)
+		return
+	}
+
+	categoryID := request.RouteInt64Param(r, "categoryID")
+	category, err := h.store.Category(request.UserID(r), categoryID)
+	if err != nil {
+		html.ServerError(w, r, err)
+		return
+	}
+
+	if category == nil {
+		html.NotFound(w, r)
+		return
+	}
+
+	categoryForm := form.CategoryForm{
+		Title:        category.Title,
+		HideGlobally: "",
+	}
+	if category.HideGlobally {
+		categoryForm.HideGlobally = "checked"
+	}
+
+	view.Set("form", categoryForm)
+	view.Set("category", category)
+	view.Set("menu", "categories")
+	view.Set("user", user)
+	view.Set("countUnread", h.store.CountUnreadEntries(user.ID))
+	view.Set("countErrorFeeds", h.store.CountUserFeedsWithErrors(user.ID))
+
+	html.OK(w, r, view.Render("edit_category"))
+}