fix(logs): fall back to neutral gray for near-black trace icon bgs

#333333 was still too close to the dark-mode surface to read. For bgs
below the luminance threshold (e.g. the MCP block's #181C1E) we now fall
back to DEFAULT_BLOCK_COLOR (#6b7280) — the same neutral the renderer
uses for blocks with no distinct identity. Clearly visible in both
themes; brighter brand colors still pass through.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: waleedlatif1

apps/sim/app/workspace/[workspaceId]/logs/components/log-details/components/trace-view/trace-view.tsx

@@ -32,6 +32,7 @@ import {
 import { cn } from '@/lib/core/utils/cn'
 import type { TraceSpan } from '@/lib/logs/types'
 import {
+  DEFAULT_BLOCK_COLOR,
   formatCostAmount,
   formatTokenCount,
   formatTps,
@@ -121,19 +122,18 @@ function iconColorClass(bgColor: string): string {
 }
 
 /**
- * Lifts a near-black icon background just enough to clear the dark-mode
- * surface. Branded colors above the threshold pass through unchanged.
+ * Near-black bgColors disappear against the dark-mode surface (--bg: #1b1b1b).
+ * Below the luminance threshold we fall back to the neutral block color used
+ * for blocks with no distinct identity; everything brighter passes through.
  */
 function adjustBgForContrast(bgColor: string): string {
   const hex = bgColor.replace('#', '')
   if (hex.length !== 6) return bgColor
   const r = Number.parseInt(hex.slice(0, 2), 16)
   const g = Number.parseInt(hex.slice(2, 4), 16)
   const b = Number.parseInt(hex.slice(4, 6), 16)
-  if (r * 299 + g * 587 + b * 114 >= 30_000) return bgColor
-  const FLOOR = 0x33
-  const lift = (c: number) => Math.max(c, FLOOR).toString(16).padStart(2, '0')
-  return `#${lift(r)}${lift(g)}${lift(b)}`
+  if (r * 299 + g * 587 + b * 114 < 30_000) return DEFAULT_BLOCK_COLOR
+  return bgColor
 }
 
 /**