Add app shell with left nav; split dashboard into top-level pages

Introduce a Layout shell with a collapsible left sidebar (state persisted
to localStorage) that becomes a hamburger drawer under md. Break the single
Dashboard into routed pages — Overview (summary tiles + node bar), Services,
Scheduled, Programs, Gateway, Mesh — nested under the shared Layout via an
Outlet. Centralize useEventStream in Layout (drop the per-page duplicates),
repoint detail-page back links at their section pages, and remove the now-dead
SectionHeader component / SECTION_HEADERS map (each page owns its header).

app/src/pages/Programs.tsx

@@ -0,0 +1,21 @@
+import { usePrograms } from "@/services/api/hooks"
+import { ProgramTable } from "@/components/ProgramTable"
+import { PageHeader } from "@/components/PageHeader"
+
+export function Programs() {
+  const { data: programs, isLoading } = usePrograms()
+
+  return (
+    <div className="max-w-6xl mx-auto px-6 py-8">
+      <PageHeader title="Programs" subtitle="Software catalog" />
+
+      {isLoading ? (
+        <p className="text-[var(--muted)]">Loading...</p>
+      ) : programs && programs.length > 0 ? (
+        <ProgramTable programs={programs} />
+      ) : (
+        <p className="text-[var(--muted)]">No programs yet.</p>
+      )}
+    </div>
+  )
+}