fix(ui): add null check for roadmap.targetAudience to prevent crash

The RoadmapHeader component crashed with "Cannot read properties of
undefined (reading 'primary')" when roadmap.targetAudience was not
yet populated. Added defensive null check to prevent black screen.

Closes #84

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <[email protected]>

auto-claude-ui/src/renderer/components/roadmap/RoadmapHeader.tsx

@@ -65,30 +65,32 @@ export function RoadmapHeader({ roadmap, competitorAnalysis, onAddFeature, onRef
       </div>
 
       {/* Target Audience */}
-      <div className="mt-4 flex items-center gap-4 text-sm">
-        <div className="flex items-center gap-2">
-          <Users className="h-4 w-4 text-muted-foreground" />
-          <span className="text-muted-foreground">Target:</span>
-          <span className="font-medium">{roadmap.targetAudience.primary}</span>
+      {roadmap.targetAudience && (
+        <div className="mt-4 flex items-center gap-4 text-sm">
+          <div className="flex items-center gap-2">
+            <Users className="h-4 w-4 text-muted-foreground" />
+            <span className="text-muted-foreground">Target:</span>
+            <span className="font-medium">{roadmap.targetAudience.primary}</span>
+          </div>
+          {roadmap.targetAudience.secondary?.length > 0 && (
+            <Tooltip>
+              <TooltipTrigger asChild>
+                <div className="text-muted-foreground cursor-help underline decoration-dotted">
+                  +{roadmap.targetAudience.secondary.length} more personas
+                </div>
+              </TooltipTrigger>
+              <TooltipContent className="max-w-md">
+                <div className="space-y-1">
+                  <div className="font-semibold mb-2">Secondary Personas:</div>
+                  {roadmap.targetAudience.secondary.map((persona) => (
+                    <div key={persona} className="text-sm">• {persona}</div>
+                  ))}
+                </div>
+              </TooltipContent>
+            </Tooltip>
+          )}
         </div>
-        {roadmap.targetAudience.secondary.length > 0 && (
-          <Tooltip>
-            <TooltipTrigger asChild>
-              <div className="text-muted-foreground cursor-help underline decoration-dotted">
-                +{roadmap.targetAudience.secondary.length} more personas
-              </div>
-            </TooltipTrigger>
-            <TooltipContent className="max-w-md">
-              <div className="space-y-1">
-                <div className="font-semibold mb-2">Secondary Personas:</div>
-                {roadmap.targetAudience.secondary.map((persona) => (
-                  <div key={persona} className="text-sm">• {persona}</div>
-                ))}
-              </div>
-            </TooltipContent>
-          </Tooltip>
-        )}
-      </div>
+      )}
 
       {/* Stats */}
       <div className="mt-4 flex items-center gap-6">