Fix status-bar overlap on scroll, and reposition/elevate the avatar menu

- Every tab now wraps its CustomScrollView in SafeArea(top: true) - the
  pinned sort/filter row was riding up underneath the status bar once
  the floating top bar above it fully collapsed, since that bar's own
  internal SafeArea only reserved the inset while it had some height
  left to put it in. Reserving it outside the scrolling region entirely
  fixes this regardless of the floating header's state. Caught live on
  device and backed by a new regression test.
- The avatar menu now covers the top bar (title included) instead of
  sitting below it - positioned off just the status-bar inset rather
  than the top bar's full height on top of that.
- The avatar menu's card now carries a second, tighter contact shadow
  alongside nooDialogShadow - that shadow alone was essentially
  invisible on a small card over a dark theme's near-black background.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.claude/context/architecture.md

@@ -297,13 +297,21 @@ bare system prompt gives no context on its own.
   matching `Scaffold.appBar`'s old `pickRequest == null` guard - see
   `buildAppTabView`'s doc comment. It sits above each tab's own pinned
   in-content header (the sort/filter controls row, or Files/Photos'
-  selection bar - see below); the two float/scroll independently.
-  `BottomNavBar` (`widgets/bottom_nav_bar.dart`) adapts
-  the pinned `AppTab`s onto `NooBottomBar`. `AppDrawer`
+  selection bar - see below); the two float/scroll independently - each
+  tab also wraps its whole `CustomScrollView` in `SafeArea(top: true,
+  bottom: false, ...)` so that pinned header stays clear of the status bar
+  once the floating top bar above it fully collapses (see
+  `topBarSliver`'s own doc comment for why that reservation can't live
+  inside the top bar itself). `BottomNavBar` (`widgets/bottom_nav_bar.dart`)
+  adapts the pinned `AppTab`s onto `NooBottomBar`. `AppDrawer`
   (`widgets/app_drawer.dart`) builds a `NooDrawer`: account block, storage
   meter, a "More" list of the hidden tabs, Settings, and an "Edit tabs"
   link (opens Settings - there's no in-page anchor to scroll to its Tabs
-  section yet).
+  section yet). `SettingsController.navMenuStyle` (Settings → Appearance →
+  "Navigation menu") offers an alternative to the hamburger/drawer pair:
+  the avatar button opens `showAvatarMenu` (`widgets/avatar_menu.dart`)
+  instead, a dropdown holding the same hidden-tabs + Settings content -
+  see `styling.md`'s Gotchas for the wiring.
 - **Desktop:** a `NooSidebar` (account card, pinned tabs, divider,
   remaining tabs, storage meter, Settings) sits beside a `NooToolbar`
   (tab title, search, an "Upload" action on Files/Photos) over the same