feat: add skeleton loading states for initial data load

- Add loading signal to DashboardContext
- Update Skeleton component to accept style prop
- Add skeleton UI to HomeRoute, LedgerRoute, and BalancesRoute
- Use Switch/Match pattern for three-state handling (loading/empty/content)

apps/miniapp/src/components/ui/skeleton.tsx

@@ -1,9 +1,11 @@
+import { JSX } from 'solid-js'
 import { cn } from '../../lib/cn'
 
 type SkeletonProps = {
   class?: string
   width?: string
   height?: string
+  style?: JSX.CSSProperties
 }
 
 export function Skeleton(props: SkeletonProps) {
@@ -12,7 +14,8 @@ export function Skeleton(props: SkeletonProps) {
       class={cn('ui-skeleton', props.class)}
       style={{
         width: props.width,
-        height: props.height
+        height: props.height,
+        ...props.style
       }}
     />
   )