fix(ui): Redirect correctly post feed removal from category feeds list

Currently, removing a feed from `/category/{id}/feeds` redirects incorrectly to `/feeds`. This change fixes it so that
removing a feed will now correctly redirect to `/category/{id}/feeds`. Removing a feed from `/feeds` is unaffected and
will work as it does currently.

To fix this, a new UI endpoint `/category/{categoryID}/feed/{feedID}/remove` is added and a corresponding handler method
to validate and perform the removal from DB.

internal/ui/category_remove_feed.go

@@ -0,0 +1,29 @@
+// 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/http/route"
+)
+
+func (h *handler) removeCategoryFeed(w http.ResponseWriter, r *http.Request) {
+	feedID := request.RouteInt64Param(r, "feedID")
+	categoryID := request.RouteInt64Param(r, "categoryID")
+
+	if !h.store.CategoryFeedExists(request.UserID(r), categoryID, feedID) {
+		html.NotFound(w, r)
+		return
+	}
+
+	if err := h.store.RemoveFeed(request.UserID(r), feedID); err != nil {
+		html.ServerError(w, r, err)
+		return
+	}
+
+	html.Redirect(w, r, route.Path(h.router, "categoryFeeds", "categoryID", categoryID))
+}