feat(shared-ui, todo): BottomStack notification system + PillNav bottomOffset

- Add NotificationBar shared component for in-stack notifications
- Add BottomNotification type and top snippet slot to BottomStack
- Add bottomOffset prop to PillNavigationProps for flexible positioning
- Remove pillNavCollapsed from todo settings (PillNav now always visible,
  toggled by layout FAB that hides all bottom bars)
- Replace floating GuestRegistrationNudge with integrated NotificationBar

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/todo/apps/web/src/lib/stores/settings.svelte.ts

@@ -74,7 +74,6 @@ export interface TodoAppSettings extends Record<string, unknown> {
 	immersiveModeEnabled: boolean;
 
 	// Navigation UI
-	pillNavCollapsed: boolean;
 	filterStripCollapsed: boolean;
 
 	// View layout
@@ -124,7 +123,6 @@ const DEFAULT_SETTINGS: TodoAppSettings = {
 	immersiveModeEnabled: false,
 
 	// Navigation UI
-	pillNavCollapsed: true, // PillNav hidden by default, shown via FAB
 	filterStripCollapsed: false, // FilterStrip shown by default when PillNav is visible
 
 	// View layout
@@ -219,9 +217,6 @@ export const todoSettings = {
 	get immersiveModeEnabled() {
 		return baseStore.settings.immersiveModeEnabled;
 	},
-	get pillNavCollapsed() {
-		return baseStore.settings.pillNavCollapsed;
-	},
 	get filterStripCollapsed() {
 		return baseStore.settings.filterStripCollapsed;
 	},
@@ -239,16 +234,7 @@ export const todoSettings = {
 	},
 
 	// Toggle methods
-	togglePillNav() {
-		baseStore.update({ pillNavCollapsed: !baseStore.settings.pillNavCollapsed });
-	},
 	toggleFilterStrip() {
 		baseStore.update({ filterStripCollapsed: !baseStore.settings.filterStripCollapsed });
 	},
-	showPillNav() {
-		baseStore.update({ pillNavCollapsed: false });
-	},
-	hidePillNav() {
-		baseStore.update({ pillNavCollapsed: true });
-	},
 };

packages/shared-ui/src/index.ts

@@ -234,8 +234,8 @@ export type {
 } from './toast';
 
 // Bottom Stack
-export { BottomStack, MinimizedTabs } from './bottom-stack';
-export type { MinimizedPage, MinimizedTabsCallbacks } from './bottom-stack';
+export { BottomStack, MinimizedTabs, NotificationBar } from './bottom-stack';
+export type { MinimizedPage, MinimizedTabsCallbacks, BottomNotification } from './bottom-stack';
 
 // Actions
 export { focusTrap } from './actions';

packages/shared-ui/src/navigation/types.ts

@@ -171,6 +171,8 @@ export interface PillNavigationProps {
 	prependElements?: PillNavElement[];
 	/** Additional elements to show after nav items (tab groups, dividers) */
 	elements?: PillNavElement[];
+	/** Bottom offset from viewport bottom (default: '0px'). Use to position above other fixed bars. */
+	bottomOffset?: string;
 }
 
 export interface NavItem {