fix(ui): keep settings sidebar open, center content, and fix worktree refresh (#1058)

* fix(ui): keep settings sidebar open, center content, and fix worktree refresh

- Prevent settings nav from collapsing on split pages (Magic Prompts, Agents, etc.)

- Center settings content with max-w-3xl for better layout on wide screens

- Widen settings window from 960px to 1200px max-width

- Fix source branch dropdown overflow with max-height and scrolling

- Add worktreeRefreshNonce to trigger immediate sidebar refresh after worktree creation

* ref(ui): address Greptile review — remove dead isNavCollapsed code and split worktree effect

- Remove isNavCollapsed variable and all dead branches (resize handle, renderSettingsNav param, SETTINGS_NAV_RAIL_WIDTH)

- Split SessionSidebar effect so worktreeRefreshNonce only triggers discoverWorktrees, not refreshGlobalSessions

- Both type-check and lint pass

* fix(ui): refine settings and worktree dropdown behavior

---------

Co-authored-by: Bohdan Triapitsyn <artmore@protonmail.com>

packages/ui/src/components/session/NewWorktreeDialog.tsx

@@ -1593,7 +1593,7 @@ export function NewWorktreeDialog({
                           <RiArrowDownSLine className="h-4 w-4 shrink-0 text-muted-foreground" />
                         </Button>
                       </DropdownMenuTrigger>
-                      <DropdownMenuContent align="start" sideOffset={6} className="w-[320px] p-0 max-h-[min(var(--available-height),24rem)] flex flex-col overflow-hidden" ref={existingBranchDropdownContentRef}>
+                      <DropdownMenuContent align="start" sideOffset={6} portalToBody className="w-[min(42rem,calc(100vw-2rem))] p-0 max-h-[min(var(--available-height),24rem)] flex flex-col overflow-hidden" ref={existingBranchDropdownContentRef}>
                         <Command shouldFilter={false}>
                         <CommandInput
                           placeholder={t('session.newWorktree.searchBranches')}
@@ -1833,7 +1833,7 @@ export function NewWorktreeDialog({
                         <RiArrowDownSLine className="h-4 w-4 shrink-0 text-muted-foreground" />
                       </Button>
                     </DropdownMenuTrigger>
-                    <DropdownMenuContent align="start" className="w-[320px] p-0" ref={sourceBranchDropdownContentRef}>
+                    <DropdownMenuContent align="start" portalToBody className="w-[min(42rem,calc(100vw-2rem))] p-0 max-h-[min(var(--available-height),24rem)] flex flex-col overflow-hidden" ref={sourceBranchDropdownContentRef}>
                       <Command shouldFilter={false}>
                         <CommandInput
                           placeholder={t('session.newWorktree.searchBranches')}