feat: unhide action, date-range filter, more sort options

- Hidden view shows an Unhide action (eye icon) instead of Hide
- Upload-date filter: From/To date range (inclusive); feed shows only videos
  published in that window (backend published_after / published_before)
- New sort options: Name (A-Z) and Channel subscribers, alongside date/views/
  duration/shuffle
- Native controls follow the theme via color-scheme (dark date picker)

frontend/src/components/Sidebar.tsx

@@ -8,6 +8,8 @@ const SORTS = [
   { id: "views", label: "Most viewed" },
   { id: "duration_desc", label: "Longest" },
   { id: "duration_asc", label: "Shortest" },
+  { id: "title", label: "Name (A–Z)" },
+  { id: "subscribers", label: "Channel subscribers" },
   { id: "shuffle", label: "Surprise me" },
 ];
 
@@ -70,7 +72,9 @@ export default function Sidebar({
     filters.includeLive ||
     filters.show !== "unwatched" ||
     filters.sort !== "newest" ||
-    !!filters.channelId;
+    !!filters.channelId ||
+    !!filters.dateFrom ||
+    !!filters.dateTo;
 
   return (
     <aside className="w-64 shrink-0 border-r border-border bg-surface/40 overflow-y-auto p-4 space-y-5 hidden md:block">
@@ -118,6 +122,41 @@ export default function Sidebar({
         </select>
       </Section>
 
+      <Section title="Upload date">
+        <div className="flex flex-col gap-1.5">
+          <label className="flex items-center justify-between gap-2 text-xs">
+            <span className="text-muted">From</span>
+            <input
+              type="date"
+              value={filters.dateFrom ?? ""}
+              onChange={(e) =>
+                setFilters({ ...filters, dateFrom: e.target.value || undefined })
+              }
+              className="bg-card border border-border rounded-md px-2 py-1 text-xs outline-none focus:border-accent"
+            />
+          </label>
+          <label className="flex items-center justify-between gap-2 text-xs">
+            <span className="text-muted">To</span>
+            <input
+              type="date"
+              value={filters.dateTo ?? ""}
+              onChange={(e) =>
+                setFilters({ ...filters, dateTo: e.target.value || undefined })
+              }
+              className="bg-card border border-border rounded-md px-2 py-1 text-xs outline-none focus:border-accent"
+            />
+          </label>
+          {(filters.dateFrom || filters.dateTo) && (
+            <button
+              onClick={() => setFilters({ ...filters, dateFrom: undefined, dateTo: undefined })}
+              className="text-[11px] text-muted hover:text-accent self-end"
+            >
+              clear dates
+            </button>
+          )}
+        </div>
+      </Section>
+
       <Section title="Content type">
         <Toggle
           label="Normal"