fix(ui): respect engaged flag in sidebar Setup pulse (#462)

The sidebar Setup item kept pulsing forever on remote/headless mcpproxy
installs because `setupIncomplete` only looked at live host predicates
(`HasConnectedClient`, `FirstMCPClientEver`), both structurally false on a
LAN server with no local AI clients and no GUI to install one in. Clicking
the wizard's "Close for now" correctly persisted `engaged: true` server-side,
but the sidebar never read it back, so the visual was "I dismissed this
five times and the dot keeps blinking."

Engagement is a deliberate, permanent signal — once the user has dismissed
the wizard, the pulse should stop. The Setup entry itself remains in the
sidebar so the user can reopen the wizard at will; only the animate-ping
halo and the count badge are gated.

The two follow-ups worth tracking but not in scope here:
  - auto-quieting irrelevant tabs on headless `env_kind` hosts
  - explicit "Hide on this host" button in the wizard footer for
    discoverability (dismiss already does the right thing under the hood
    now that the sidebar honors it)

Closes #461

Co-authored-by: Claude Code <noreply@anthropic.com>

Author: Dumbris

frontend/src/components/SidebarNav.vue

@@ -402,8 +402,17 @@ const onboardingStore = useOnboardingStore()
 
 // Spec 046 v2: badge count drives the sidebar Setup entry's pulse + count.
 // Refetched on mount; the wizard itself drives subsequent updates while open.
+//
+// Pulse is also gated on `!isEngaged` so that headless / LAN-server installs
+// (where HasConnectedClient and FirstMCPClientEver are structurally false —
+// there's no local AI client and no GUI to install one) can quiet the badge
+// by clicking "Close for now". The Setup entry itself remains in the sidebar
+// so the user can re-open the wizard, but it no longer pulses or shows a
+// count after engagement.
 const setupCount = computed(() => onboardingStore.incompleteTabCount)
-const setupIncomplete = computed(() => setupCount.value > 0)
+const setupIncomplete = computed(
+  () => setupCount.value > 0 && !onboardingStore.isEngaged
+)
 const setupTitleAttr = computed(() =>
   setupIncomplete.value
     ? `Setup (${setupCount.value} step${setupCount.value === 1 ? '' : 's'} remaining)`