- Add isImmersiveMode state to appStore for global fullscreen management
- Update AppShell to hide Header and Sidebar when immersive mode is active
- Add fullscreen toggle button to workflow and knowledge pages:
- TerminalDashboardPage, IssueHubPage, SessionsPage, LiteTasksPage
- HistoryPage, TeamPage, MemoryPage, SkillsManagerPage
- CommandsManagerPage, RulesManagerPage, CliViewerPage
- OrchestratorPage (via FlowToolbar)
- Preserve padding in fullscreen mode for better visual appearance