refactor: remove explore tab, simplify to 3-tab layout (Home, Progress, Profile)

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

app/_layout.tsx

@@ -25,6 +25,7 @@ import {
 import { PostHogProvider } from 'posthog-react-native'
 
 import { ThemeProvider, useThemeColors } from '@/src/shared/theme'
+import { TEXT, NAVY } from '@/src/shared/constants/colors'
 import { useUserStore } from '@/src/shared/stores'
 import { useNotifications } from '@/src/shared/hooks'
 import { initializePurchases } from '@/src/shared/services/purchases'
@@ -120,12 +121,11 @@ function RootLayoutInner() {
               name="workout/[id]"
               options={{
                 headerShown: true,
-                headerTransparent: true,
-                headerBlurEffect: colors.colorScheme === 'dark' ? 'dark' : 'light',
+                headerStyle: { backgroundColor: colors.bg.base },
                 headerShadowVisible: false,
                 headerTitle: '',
                 headerBackButtonDisplayMode: 'minimal',
-                headerTintColor: colors.colorScheme === 'dark' ? '#FFFFFF' : '#000000',
+                headerTintColor: colors.text.primary,
                 animation: 'slide_from_right',
               }}
             />
@@ -139,12 +139,11 @@ function RootLayoutInner() {
               name="program/[id]"
               options={{
                 headerShown: true,
-                headerTransparent: true,
-                headerBlurEffect: colors.colorScheme === 'dark' ? 'dark' : 'light',
+                headerStyle: { backgroundColor: colors.bg.base },
                 headerShadowVisible: false,
                 headerTitle: '',
                 headerBackButtonDisplayMode: 'minimal',
-                headerTintColor: colors.colorScheme === 'dark' ? '#FFFFFF' : '#000000',
+                headerTintColor: colors.text.primary,
                 animation: 'slide_from_right',
               }}
             />
@@ -173,15 +172,6 @@ function RootLayoutInner() {
                 animation: 'fade',
               }}
             />
-            <Stack.Screen
-              name="explore-filters"
-              options={{
-                presentation: 'formSheet',
-                headerShown: false,
-                sheetGrabberVisible: true,
-                sheetAllowedDetents: [0.5],
-              }}
-            />
           </Stack>
       </View>
     </QueryClientProvider>