style(type): raise the too-small toolbar and filter text toward the view-switcher size

The view-switcher's 16px reads comfortably; the toolbar and filter controls sat at 12px. Bring
the marked controls up to match, and lift the general scale on the shared filter surfaces.

- Toolbar (feed + channel + Plex, via the shared components): FilterSelect and SortControl trigger
  pills text-xs → text-base (16px, the view-switcher size); the result count → text-sm; the
  active-filter chips → text-sm with the "FILTERED BY" label text-2xs → text-xs.
- Filterbar: the Combobox picker input → text-base (matching the toolbar pills) + its chips → text-sm;
  the panel/widget headers (SidePanel collapsed-rail + panel title, PanelGroup widget titles) up one step.

Channel info and the manager tables were already at 14–16px (readable), so they were left as-is.

frontend/src/components/SidePanel.tsx

@@ -74,7 +74,7 @@ export default function SidePanel({
           </span>
         )}
         <span
-          className="text-2xs font-semibold uppercase tracking-[0.18em] text-muted"
+          className="text-xs font-semibold uppercase tracking-[0.18em] text-muted"
           style={{ writingMode: "vertical-rl", transform: "rotate(180deg)" }}
         >
           {title}
@@ -98,7 +98,7 @@ export default function SidePanel({
               {pinned ? <PinOff className="w-4 h-4" /> : <Pin className="w-4 h-4" />}
             </button>
             <span className="shrink-0 flex text-accent">{icon}</span>
-            <span className="flex-1 min-w-0 truncate text-xs font-bold uppercase tracking-[0.12em]">
+            <span className="flex-1 min-w-0 truncate text-sm font-bold uppercase tracking-[0.12em]">
               {title}
             </span>
             {count > 0 && (