swarm-ui: one subdirectory per ui/ component

Per mara's PR review request: Panel/StatusChip/Table each move into
their own subdir (ui/panel/, ui/status-chip/, ui/table/) colocating
the component with its stylesheet, matching shell/ (Shell.tsx +
Shell.css already lived this way). Import paths in App.tsx and
swarm-ui.css updated to match; no behavior change.

npm run build + typecheck both clean.

frontend/packages/swarm-ui/src/ui/Panel.tsx

@@ -1,14 +0,0 @@
-// <Panel> — the one generic container primitive every route needs: a
-// bordered surface with an optional title, no other opinions. Not a
-// card-with-actions/footer/whatever kit — those get added the first
-// time a real page actually needs one, not speculatively ahead of it.
-import type { ComponentChildren } from 'preact';
-
-export function Panel({ title, children }: { title?: string; children: ComponentChildren }) {
-  return (
-    <section class="ui-panel">
-      {title ? <h2 class="ui-panel-title">{title}</h2> : null}
-      <div class="ui-panel-body">{children}</div>
-    </section>
-  );
-}