feat(a11y): add i18n keys for accessibility labels

frontend/src/i18n/lang/en.json

@@ -500,7 +500,8 @@
       "bucketTitleSavedSuccess": "The bucket title has been saved successfully.",
       "bucketLimitSavedSuccess": "The bucket limit been saved successfully.",
       "collapse": "Collapse this bucket",
-      "bucketLimitReached": "You have reached the bucket limit. Remove tasks or increase the limit to add new tasks."
+      "bucketLimitReached": "You have reached the bucket limit. Remove tasks or increase the limit to add new tasks.",
+      "bucketOptions": "Bucket options"
     },
     "pseudo": {
       "favorites": {
@@ -740,7 +741,9 @@
     "upcoming": "Upcoming",
     "settings": "Settings",
     "imprint": "Imprint",
-    "privacy": "Privacy Policy"
+    "privacy": "Privacy Policy",
+    "closeSidebar": "Close sidebar",
+    "home": "Vikunja home"
   },
   "misc": {
     "loading": "Loading…",
@@ -775,9 +778,15 @@
     "createdBy": "Created by {0}",
     "actions": "Actions",
     "cannotBeUndone": "This cannot be undone!",
-    "avatarOfUser": "{user}'s profile image"
+    "avatarOfUser": "{user}'s profile image",
+    "closeBanner": "Close banner",
+    "closeDialog": "Close dialog",
+    "closeQuickActions": "Close quick actions",
+    "skipToContent": "Skip to main content",
+    "sortBy": "Sort by"
   },
   "input": {
+    "projectColor": "Project color",
     "resetColor": "Reset Color",
     "datepicker": {
       "today": "Today",
@@ -972,6 +981,8 @@
       "back": "Back to project",
       "due": "Due {at}",
       "closePopup": "Close popup",
+      "closeTaskDetail": "Close task detail",
+      "markAsDone": "Mark '{task}' as done",
       "scrollToBottom": "Scroll to bottom",
       "organization": "Organization",
       "management": "Management",