feat: browser sidebar tabs, split view & central wisp config

- Add collapsible/resizable vertical sidebar tabs with layout picker
- Add split-view (two tabs side by side, middle-click opens in other pane)
- Add command palette inside browser (Ctrl+Shift+P) with actions, tabs, bookmarks
- Improve back/forward nav stack handling and default favicons
- Change Run dialog shortcut from Ctrl+R to Ctrl+Alt+R

Author: Reeyuki

README.md

@@ -259,7 +259,7 @@ config editing.
 
 ## 🌐 Browser & Internet
 
-- Yuki Browser with bookmarks, proxy, tor, history, dark mode, tab system,screenshot
+- Yuki Browser with Sidebar Tabs mode, bookmarks, proxy, tor, history, dark mode, tab system,screenshot
 - WebTorrent Client
 - Tor Manager - tor browsing via WASM-based Tor client with Snowflake transport
 - VNC Client using novnc