[Layout] Base (#6907)

* Add common gutter styles as hook

* Add computed scrollbar gutter CSS vars

* Add new layout components

* Replace layout components in settings screens

* Remove old back button

* Invert web border logic for easier migration

* Clean up Slot API

* Port over FF handling of scrollbar offset

* Trade boilerplate for ease of use

* Limit to one line

* Allow two lines, fix wrapping

* Fix alignment

* sticky headers

* set max with on header and center

* [Layout] Notifications Header (#6910)

* Replace notifications screen header

* fix cropped indicator

---------

Co-authored-by: Samuel Newman <mozzius@protonmail.com>

* Replace Hashtag header (#6928)

* [Layout] ChatList header (#6929)

* Replace ChatList header

* update chat settings as well

---------

Co-authored-by: Samuel Newman <mozzius@protonmail.com>

* Add web borders to Chat settings

* Remove unused var

* Move ChatList header outside center

* Replace empty chat layout

* fix breakpoints

* [Layout] Scrollbar gutters (#6908)

* Fix sidebar alignment

* Make sure scrollbars don't hide

* Gift left nav more space

* Use stable one-edge, update logic in RightNav

* Ope

* Increase width

* Reset

* Add transform to sidebars

* Remove bg in sidebars

* Handle shifts in layout components

* Replace scroll-removal handling

* Make react-remove-scroll an explicit dep

* Remove unused script

* use correct scroll insets (#6950)

* [Layout] Feeds headers (#6913)

* Replace ViewHeader internals, duplicate old ViewHeader

* Replace Feeds header

* Replace SavedFeeds header

* Visual alignment

* Uglier but clear

* Use old ViewHeader for SavedFeeds

* use Layout.Center instead of Layout.Content

* use left-aligned header for feed edit

* delete unused old view header

---------

Co-authored-by: Samuel Newman <mozzius@protonmail.com>

* [Layout] Every other screen (#6953)

* attempt to fix double borders on every other screen

* delete ListHeaderDesktop

* delete `SimpleViewHeader` and fix screens (#6956)

* Make Layout.Center not full height

* Refactor List to use Layout.Center, remove built-in borders

* Fix Home screen

* Refactor PagerWithHeader to use Layout components

* Replace components in ProfileFeed and ProfileList

* Borders on Profile

* Search screen replacements

* use new header for profile subpage header (#6958)

* Search AutocompleteResults

* use new header for starter pack wizard (#6957)

* Fix post thread

* Enable borders by default

* Moderation muted and blocked accounts

* Fix scrollbar offset on Labeler

* Remove ScrollView from Moderation

* Remove ScrollView from Deactivated

* Remove ScrollView from onboarding

* Remove ScrollView from SignupQueued

* Mark deprecations

* fix lint

* Fix double borders on profile load

* Remove unneeded CenteredView from noty Feed

* Remove double Center layout on Notifications screen

* Remove double Center layout on ChatList screen

* Handle scrollbar offset in chat

* Use new atom for other scrollbar offsets

* Remove borders from old views

* Better doc

* Remove temp migration prop

* Fix new atom usage on native

* Clean up Hashtag screen

* Layout docs

* Clarify usage in Pager

* Handle nested offset contexts

* Clean up Layout

* fix feeds page

* asymmetric header on native (#6969)

* Reusable header const

* Fix up home header

* Add back button to convo

* Add hitslop to header buttons

* Comment

* Better handling on native for new atom

* Format

* Fix nested flatlist on mod screens

* Use react-remove-scroll-bar directly

* Fix notification count overflow on web

* Clarify doc

---------

Co-authored-by: Samuel Newman <mozzius@protonmail.com>

src/view/com/pager/PagerWithHeader.web.tsx

@@ -1,10 +1,10 @@
 import * as React from 'react'
-import {ScrollView, StyleSheet, View} from 'react-native'
+import {ScrollView, View} from 'react-native'
 import {useAnimatedRef} from 'react-native-reanimated'
 
-import {usePalette} from '#/lib/hooks/usePalette'
-import {useWebMediaQueries} from '#/lib/hooks/useWebMediaQueries'
 import {Pager, PagerRef, RenderTabBarFnProps} from '#/view/com/pager/Pager'
+import {atoms as a, web} from '#/alf'
+import * as Layout from '#/components/Layout'
 import {ListMethods} from '../util/List'
 import {TabBar} from './TabBar'
 
@@ -121,30 +121,19 @@ let PagerTabBar = ({
   onSelect?: (index: number) => void
   tabBarAnchor?: JSX.Element | null | undefined
 }): React.ReactNode => {
-  const pal = usePalette('default')
-  const {isMobile} = useWebMediaQueries()
   return (
     <>
-      <View
-        style={[
-          !isMobile && styles.headerContainerDesktop,
-          pal.border,
-          !isHeaderReady && styles.loadingHeader,
-        ]}>
-        {renderHeader?.()}
-      </View>
+      <Layout.Center>{renderHeader?.()}</Layout.Center>
       {tabBarAnchor}
-      <View
-        style={[
-          styles.tabBarContainer,
-          isMobile
-            ? styles.tabBarContainerMobile
-            : styles.tabBarContainerDesktop,
-          pal.border,
+      <Layout.Center
+        style={web([
+          a.sticky,
+          a.z_10,
           {
+            top: 0,
             display: isHeaderReady ? undefined : 'none',
           },
-        ]}>
+        ])}>
         <TabBar
           testID={testID}
           items={items}
@@ -154,7 +143,7 @@ let PagerTabBar = ({
           dragProgress={undefined as any /* native-only */}
           dragState={undefined as any /* native-only */}
         />
-      </View>
+      </Layout.Center>
     </>
   )
 }
@@ -180,33 +169,6 @@ function PagerItem({
   })
 }
 
-const styles = StyleSheet.create({
-  headerContainerDesktop: {
-    marginHorizontal: 'auto',
-    width: 600,
-    borderLeftWidth: 1,
-    borderRightWidth: 1,
-  },
-  tabBarContainer: {
-    // @ts-ignore web-only
-    position: 'sticky',
-    top: 0,
-    zIndex: 1,
-  },
-  tabBarContainerDesktop: {
-    marginHorizontal: 'auto',
-    width: 600,
-    borderLeftWidth: 1,
-    borderRightWidth: 1,
-  },
-  tabBarContainerMobile: {
-    paddingHorizontal: 0,
-  },
-  loadingHeader: {
-    borderColor: 'transparent',
-  },
-})
-
 function toArray<T>(v: T | T[]): T[] {
   if (Array.isArray(v)) {
     return v