Redesign Display Settings, Wallpapers, Booru; add System Monitor, Weather

Display Settings: drag-to-arrange multi-monitor canvas with edge
snapping (locked when only one screen is connected), 8/10-bit depth,
color management presets (sRGB/Wide/EDID/HDR+EDID), SDR
brightness/saturation, ICC profile path, VRR toggle. display-set now
takes a single pre-built descriptor instead of a fixed positional arg
list, since Hyprland's monitor keyword grew well past that.

Wallpapers: fixed the current-wallpaper highlight never loading on
open, added real first-frame thumbnails for animated wallpapers
(wallpaper-thumbs + ffmpeg), bigger 2-column grid, filename filter.

Booru: separate downloads folder from Wallpapers so browsing doesn't
clutter the wallpaper picker, bigger grid, Safe/Moderate/Explicit
rating tiers replacing the old binary toggle, sort order (Newest/
Score/Random). Fixed pagination being completely broken (a Flow
anchor violation was silently disabling the whole layout) and
Danbooru's Random sort (order:random tag times out server-side --
switched to their random=true endpoint for that case).

Wi-Fi panel: added a "Scanning.../No networks found" state and a
manual rescan button -- previously showed nothing either way, making
"still scanning" indistinguishable from a real failure.

Bluetooth: auto-scans on open like Wi-Fi now, instead of requiring a
manual click every time.

New: System Monitor panel (CPU/RAM/GPU/VRAM/disk usage, NVIDIA or AMD
detected automatically) and Weather panel (IP-geolocated or a typed
city, current + hourly forecast, Open-Meteo, no API key) with a
compact taskbar badge.

dotfiles/quickshell/RightBar.qml

@@ -173,6 +173,16 @@ PanelWindow {
                 active: root.activePanel === "devices"
                 onClicked: root.toggle("devices")
             }
+            SidebarRow {
+                label: "System Monitor"
+                active: root.activePanel === "system"
+                onClicked: root.toggle("system")
+            }
+            SidebarRow {
+                label: "Weather"
+                active: root.activePanel === "weather"
+                onClicked: root.toggle("weather")
+            }
         }
     }