Remove Mistake Analyzer and rename Mistake Heatmap to Mastery Map

src/app/dashboard/layout.tsx

@@ -230,7 +230,7 @@ export default function DashboardLayout({ children }: { children: ReactNode }) {
             section="ai"
             href="/dashboard/ai-coach/heatmap" 
             icon={<Flame size={17} />} 
-            label="Mistake Heatmap" 
+            label="Mastery Map" 
             active={pathname.startsWith("/dashboard/ai-coach/heatmap")} 
             isLocked={!hasAccessTo("ai-mistake-tracking")}
           />
@@ -242,14 +242,7 @@ export default function DashboardLayout({ children }: { children: ReactNode }) {
             active={pathname.startsWith("/dashboard/ai-coach/weekly-progress")} 
             isLocked={!hasAccessTo("detailed-performance-analytics")}
           />
-          <NavItem 
-            section="ai"
-            href="/dashboard/ai-coach/mistakes" 
-            icon={<BrainCircuit size={17} />} 
-            label="Mistake Analyzer" 
-            active={pathname.startsWith("/dashboard/ai-coach/mistakes")} 
-            isLocked={!hasAccessTo("ai-mistake-tracking")}
-          />
+
         </nav>
         
         {/* Bottom Settings + Profile */}