feat(llm): use dim italic for insights error with aligned section header

Render insights errors with the standard dashSectionHeader pill and a
DashSubtitle (gray dim italic) message instead of bold vermillion, so
the error reads as a non-critical degradation aligned with the other
dashboard sections.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: cpcloud

internal/app/dashboard.go

@@ -596,7 +596,8 @@ func (m *Model) dashboardView(budget, maxWidth int) string {
 		}
 		dimmed := cursorSection != "" && cursorSection != dashSectionInsights
 		hdr := m.dashSectionHeader(dashSectionInsights, 0, dimmed)
-		lines = append(lines, hdr, "  "+m.styles.Error().Render("error: "+m.dash.insights.err.Error()))
+		msg := m.styles.DashSubtitle().Render("  unavailable: " + m.dash.insights.err.Error())
+		lines = append(lines, hdr, msg)
 	}
 
 	// Staleness indicator for insights section header.

internal/app/dashboard_test.go

@@ -1334,7 +1334,9 @@ func TestInsightsSection_ErrorState(t *testing.T) {
 	m.buildDashNav()
 
 	view := m.dashboardView(50, 80)
+	assert.Contains(t, view, "unavailable")
 	assert.Contains(t, view, "network timeout")
+	assert.NotContains(t, view, "error:")
 }
 
 func TestInsightsNav_JumpsToEntity(t *testing.T) {