fix(app): improve light mode theming

- Make PaseoLogo theme-aware (uses foreground color instead of hardcoded white)
- Add shadow tokens (sm/md/lg) to theme with per-scheme opacity, radius, and offset
- Replace all 16 hardcoded shadow instances with spreadable theme.shadow tokens
- Fix button icon color for default variant (use accentForeground, not foreground)
- Fix dark background flash on startup (root layout used hardcoded darkTheme)
- Add theme.colorScheme to replace fragile hex-string dark mode detection
- Add scrollbarHandle and surfaceWorkspace tokens to eliminate isDark branching

packages/app/src/components/ui/autocomplete.tsx

@@ -248,11 +248,7 @@ const styles = StyleSheet.create(((theme: Theme) => ({
     borderRadius: theme.borderRadius.lg,
     paddingHorizontal: theme.spacing[3],
     paddingVertical: theme.spacing[3],
-    shadowColor: "#000",
-    shadowOffset: { width: 0, height: 4 },
-    shadowOpacity: 0.2,
-    shadowRadius: 8,
-    elevation: 8,
+    ...theme.shadow.md,
   },
   detailLabel: {
     color: theme.colors.foreground,
@@ -275,11 +271,7 @@ const styles = StyleSheet.create(((theme: Theme) => ({
     borderColor: theme.colors.borderAccent,
     borderRadius: theme.borderRadius.lg,
     overflow: "hidden",
-    shadowColor: "#000",
-    shadowOffset: { width: 0, height: 4 },
-    shadowOpacity: 0.2,
-    shadowRadius: 8,
-    elevation: 8,
+    ...theme.shadow.md,
   },
   scrollView: {
     flexGrow: 0,

packages/app/src/components/ui/button.tsx

@@ -136,9 +136,11 @@ export function Button({
       return <View>{leftIcon}</View>;
     }
 
-    const color = variant === "ghost"
-      ? (isGhostHovered ? theme.colors.foreground : theme.colors.foregroundMuted)
-      : theme.colors.foreground;
+    const color = variant === "default"
+      ? theme.colors.accentForeground
+      : variant === "ghost"
+        ? (isGhostHovered ? theme.colors.foreground : theme.colors.foregroundMuted)
+        : theme.colors.foreground;
     const iconSize = ICON_SIZE[size];
 
     // Render function

packages/app/src/components/ui/combobox.tsx

@@ -845,11 +845,7 @@ const styles = StyleSheet.create((theme) => ({
     borderRadius: theme.borderRadius.lg,
     borderWidth: 1,
     borderColor: theme.colors.border,
-    shadowColor: "#000",
-    shadowOffset: { width: 0, height: 4 },
-    shadowOpacity: 0.2,
-    shadowRadius: 8,
-    elevation: 8,
+    ...theme.shadow.md,
     maxHeight: 400,
     overflow: "hidden",
   },

packages/app/src/components/ui/context-menu.tsx

@@ -722,11 +722,7 @@ const styles = StyleSheet.create((theme) => ({
     borderWidth: 1,
     borderColor: theme.colors.border,
     borderRadius: theme.borderRadius.lg,
-    shadowColor: "#000",
-    shadowOffset: { width: 0, height: 4 },
-    shadowOpacity: 0.2,
-    shadowRadius: 8,
-    elevation: 8,
+    ...theme.shadow.md,
     overflow: "hidden",
   },
   sheetBackground: {

packages/app/src/components/ui/dropdown-menu.tsx

@@ -605,11 +605,7 @@ const styles = StyleSheet.create((theme) => ({
     borderColor: theme.colors.borderAccent,
     borderRadius: theme.borderRadius.lg,
     overflow: "hidden",
-    shadowColor: "#000",
-    shadowOffset: { width: 0, height: 4 },
-    shadowOpacity: 0.2,
-    shadowRadius: 8,
-    elevation: 8,
+    ...theme.shadow.md,
   },
   labelContainer: {
     paddingHorizontal: theme.spacing[3],

packages/app/src/components/ui/tooltip.tsx

@@ -535,11 +535,7 @@ const styles = StyleSheet.create((theme) => ({
     backgroundColor: theme.colors.popover,
     borderWidth: theme.borderWidth[2],
     borderColor: theme.colors.border,
-    shadowColor: "#000",
-    shadowOpacity: 0.2,
-    shadowRadius: 12,
-    shadowOffset: { width: 0, height: 6 },
-    elevation: 6,
+    ...theme.shadow.sm,
     zIndex: 1000,
   },
 }));