Add Authentik sign-in, fix tab scroll insets, and polish multi-account auth.

Mobile app detects SSO per server, supports OAuth sign-in, and preserves saved
sessions when adding accounts. Tab screens get proper chrome layout and tab-bar
clearance with scrollable page headers.

Co-authored-by: Cursor <cursoragent@cursor.com>

components/TabScrollView.tsx

@@ -1,16 +1,20 @@
-import type { ReactNode } from "react";
+import { useScrollToTop } from "expo-router";
+import { useRef, type ReactNode } from "react";
 import { Platform, ScrollView, type ScrollViewProps, StyleSheet, View } from "react-native";
 
 import { tabLayout } from "@/lib/tab-layout";
-import { useTabBarScrollPadding } from "@/lib/tab-bar-insets";
+import { useTabScreenScrollPadding } from "@/lib/tab-bar-insets";
 
 type TabScrollViewProps = ScrollViewProps & {
-  /** Rendered above screen body — scrolls under the blurred top chrome. */
+  /** Rendered at the top of scroll content (scrolls with the page). */
   header?: ReactNode;
   children: ReactNode;
 };
 
-/** Scroll view for native tab screens — content scrolls under the tab bar. */
+/**
+ * Tab screen scroll view. Top chrome (logo / account) is pinned in TabPage;
+ * the page header and body scroll together here.
+ */
 export function TabScrollView({
   header,
   children,
@@ -18,18 +22,22 @@ export function TabScrollView({
   style,
   ...props
 }: TabScrollViewProps) {
-  const scrollPadding = useTabBarScrollPadding();
+  const scrollRef = useRef<ScrollView>(null);
+  const bottomPadding = useTabScreenScrollPadding();
+
+  useScrollToTop(scrollRef);
 
   return (
     <ScrollView
+      ref={scrollRef}
       style={[styles.scroll, style]}
       contentContainerStyle={[
         tabLayout.scrollContent,
-        { paddingBottom: scrollPadding },
+        { paddingBottom: bottomPadding },
         contentContainerStyle,
       ]}
       contentInsetAdjustmentBehavior={Platform.OS === "ios" ? "never" : undefined}
-      scrollIndicatorInsets={{ bottom: scrollPadding }}
+      scrollIndicatorInsets={{ bottom: bottomPadding }}
       {...props}
     >
       {header}
@@ -41,6 +49,7 @@ export function TabScrollView({
 const styles = StyleSheet.create({
   scroll: {
     flex: 1,
+    minHeight: 0,
     backgroundColor: "transparent",
   },
 });