fix(frontend): finish the token migration — raw grey classes -> theme tokens

UI_REDESIGN chunk 4 was never finished: 39 app/component files still used
raw Tailwind greys, kept readable in light mode only by the !important
override sheet. In dark mode text-gray-600 is ~2.3:1 on surface, and the
light override maps it to #94a3b8 (~2.6:1 on white) — unreadable in both.

Mechanical mapping (886 classes): gray-100/200 -> ink, 300/400 -> ink-2,
500/600/700 -> ink-muted, bg 950/900/800 -> page/surface/raised,
border 800 -> line, 700/600 -> line-strong, plus hover/divide/placeholder.
Alpha suffixes kept (tokens are color-mix, so /60 works). bg-gray-700,
text-white and marketing pages left alone. text-[9px] -> text-[10px].

Frontend unverified: no Node on the authoring box (#207).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

drb-frontend/components/StatusBadge.tsx

@@ -3,7 +3,7 @@ import type { NodeStatus } from "@/lib/types";
 const styles: Record<NodeStatus, string> = {
   online:       "bg-green-950 text-green-400 border border-green-800",
   recording:    "bg-orange-950 text-orange-400 border border-orange-800 animate-pulse",
-  offline:      "bg-gray-900 text-gray-500 border border-gray-700",
+  offline:      "bg-surface text-ink-muted border border-line-strong",
   unconfigured: "bg-indigo-950 text-indigo-400 border border-indigo-800",
 };