feat(feed): flatten the filter rail — dropdown upload-date, non-collapsible widgets, title triggers

Rework the feed filter rail into simpler label + control rows:
- Remove the rail's own "Clear all" (the chip row above the cards already
  surfaces one whenever any filter is active).
- Replace the Upload date chip group with a single-select dropdown
  (DateFilterSelect): an "Any time" clear, more presets (2 weeks / 3 months /
  2 years / 5 years) and a "Custom range" that reveals from/to on select; the
  trigger then reads the chosen range. Selection logic is the pure lib/dateFilter
  (applyDateChip -> selectDateChip, no toggle-off; tests updated).
- Widgets are no longer collapsible: PanelGroup gains `collapsible` (feed passes
  false) so groups render as always-open label + control rows; reorder + hide in
  edit mode stay. Other rails (Plex/Playlists) keep the collapsible islands.
- A non-collapsible group's title can act as its own trigger (PanelItem
  onTitleClick): "Your tags" opens the tag manager, replacing the inline Manage
  button.

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

@@ -67,9 +67,19 @@
   "datePreset": {
     "24h": "24h",
     "1week": "1 week",
+    "2weeks": "2 weeks",
     "1month": "1 month",
+    "3months": "3 months",
     "6months": "6 months",
-    "1year": "1 year"
+    "1year": "1 year",
+    "2years": "2 years",
+    "5years": "5 years"
+  },
+  "date": {
+    "anyTime": "Any time",
+    "customRange": "Custom range",
+    "fromShort": "From {{date}}",
+    "untilShort": "Until {{date}}"
   },
   "channelSearch": "Search channels…",
   "noChannelMatch": "No channel matches.",

frontend/src/i18n/locales/hu/sidebar.json

@@ -67,9 +67,19 @@
   "datePreset": {
     "24h": "24 óra",
     "1week": "1 hét",
+    "2weeks": "2 hét",
     "1month": "1 hónap",
+    "3months": "3 hónap",
     "6months": "6 hónap",
-    "1year": "1 év"
+    "1year": "1 év",
+    "2years": "2 év",
+    "5years": "5 év"
+  },
+  "date": {
+    "anyTime": "Bármikor",
+    "customRange": "Egyéni tartomány",
+    "fromShort": "{{date}}-től",
+    "untilShort": "{{date}}-ig"
   },
   "channelSearch": "Csatornák keresése…",
   "noChannelMatch": "Nincs találat.",