Add Foundry mobile layout with Tauri iOS/Android support

- Add responsive mobile layout with bottom pill tab bar, swipe navigation, and task list as home screen
- Add platform detection (useIsMobile hook) with viewport breakpoint and VITE_MOBILE build flag
- Mobile-optimize settings/billing/account pages (single-column layout with horizontal tabs)
- Add iOS safe area inset handling with 47px minimum padding
- Scaffold Tauri v2 mobile targets (iOS/Android) with platform-gated sidecar and capabilities
- Add notification sound support and mobile build script

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

foundry/packages/desktop/src-tauri/gen/apple/foundry.xcodeproj/project.xcworkspace/contents.xcworkspacedata

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Workspace
+   version = "1.0">
+   <FileRef
+      location = "self:">
+   </FileRef>
+</Workspace>

foundry/packages/desktop/src-tauri/gen/apple/foundry.xcodeproj/project.xcworkspace/xcshareddata/WorkspaceSettings.xcsettings

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>BuildSystemType</key>
+	<string>Original</string>
+	<key>DisableBuildSystemDeprecationDiagnostic</key>
+	<true/>
+</dict>
+</plist>