fix(mobile): show the bundled whale on DeepSeek Build tabs (#31359)

fix(mobile): reuse DeepSeek whale for Build tabs
Adapted from community PR #30525 with a focused component regression and native current-shell validation.

test(mobile): use checked icon renderer guard


test(mobile): keep icon diagnostic with review evidence
Native before/after captures cover this low-impact asset mapping; retain the local fail/pass diagnostic outside the product diff.

Use checked optional type for mobile icon lookup

Co-authored-by: Wooseong Kim <innocarpe@gmail.com>

mobile/src/components/MobileAgentIcon.tsx

@@ -1,13 +1,14 @@
 import { Image, StyleSheet, Text, View } from 'react-native'
 import type { ImageSourcePropType } from 'react-native'
 import { Terminal } from 'lucide-react-native'
-import type { TuiAgent } from '../../../src/shared/tui-agent'
 import Svg, { Defs, G, LinearGradient, Path, Stop } from 'react-native-svg'
 import { colors } from '../theme/mobile-theme'
 import { MOBILE_AGENT_CATALOG } from '../tasks/mobile-agent-catalog'
 import { MOBILE_AGENT_ICON_ASSETS } from './mobile-agent-icon-assets'
 import { ClaudeIcon, OpenAIIcon } from './AgentIcons'
 
+const iconAssets: Partial<Record<string, ImageSourcePropType>> = MOBILE_AGENT_ICON_ASSETS
+
 // Why: agent branding should match the desktop/new-worktree picker everywhere
 // mobile lets users choose the agent that will own a workspace.
 
@@ -107,7 +108,8 @@ export function MobileAgentIcon({ agentId, size = 16 }: { agentId: string; size?
 
   // Why: prefer the favicon bundled into the app over Google's favicon service,
   // which is unreachable in some regions and offline (#8451).
-  const bundledIcon = MOBILE_AGENT_ICON_ASSETS[agentId as TuiAgent]
+  const iconAgentId = agentId === 'dsb' ? 'dsh' : agentId
+  const bundledIcon = iconAssets[iconAgentId]
   if (bundledIcon) {
     return <BundledIcon source={bundledIcon} size={size} />
   }