restore: reapply 50d95fa UI foundation clobbered by sync in 2ee1fe9

My rsync --delete based deploy sync overwrote the working tree with a stale
local copy and accidentally reverted commit 50d95fa (V2 Design-Fundament,
task ea7c2063) — new ui/ components deleted, token/color work in
dashboard/v2 and nexus-tokens.css rolled back. This restores all 17 files
exactly from 50d95fa; no overlap with the modal rework files (TaskBoardView,
tasks store, BoardCard), which stay as committed in 2ee1fe9.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/components/dashboard/v2/AgentNode.vue

@@ -157,7 +157,7 @@ defineEmits<{
 
 .nc-av.iris-av {
   background: var(--grad);
-  color: #fff;
+  color: var(--tx);
   box-shadow: var(--glow-purple);
 }
 
@@ -255,7 +255,7 @@ defineEmits<{
 }
 
 .node.is-work .nc-bar i {
-  background: linear-gradient(90deg, #2bb87f, #3ddc97);
+  background: linear-gradient(90deg, var(--st-work), var(--st-work));
 }
 
 /* ── Meta ────────────────────────────────────── */