feat(views): saved-views UI — sidebar widget, apply/rename/default/reorder/share

A new "Saved views" filter-sidebar widget (SavedViewsWidget): save the
current filters under a name, apply one with a click (active-highlighted
when it matches), rename, delete (confirm), drag-reorder, share by link
(reuses shareUrl), and star one as the default. The default view's filters
are mirrored to localStorage so loadInitialFilters applies it synchronously
on load/F5 (an api/url share link still wins; no default → last-session
filters as before). Hidden for the demo account. EN/HU/DE.

frontend/src/i18n/locales/en/views.json

@@ -0,0 +1,16 @@
+{
+  "save": "Save current view",
+  "namePlaceholder": "View name",
+  "saveAction": "Save",
+  "cancel": "Cancel",
+  "empty": "No saved views yet. Filter the feed, then save it.",
+  "apply": "Apply this view",
+  "makeDefault": "Set as default (loads on start)",
+  "isDefault": "Default view — loads on start",
+  "share": "Copy a link to this view",
+  "shareCopied": "View link copied",
+  "rename": "Rename",
+  "delete": "Delete",
+  "deleteConfirm": "Delete the saved view “{{name}}”?",
+  "reorder": "Drag to reorder"
+}