Add keyboard shortcuts for worktree actions and dynamic shortcut display

Replace all hardcoded shortcut key rendering with useShortcutKeys() so
rebound shortcuts always display correctly. Add Cmd+O (new worktree),
Cmd+Shift+Backspace (archive worktree) with proper active-project
scoping. Show shortcut hints in tooltips and dropdown menus. Fix tooltip
alignment to center, bump dropdown menu surface level, simplify
TerminalPane to single-terminal, and add special key display symbols.

packages/app/src/components/left-sidebar.tsx

@@ -745,7 +745,7 @@ function DesktopSidebar({
             <TooltipContent side="top" align="center" offset={8}>
               <View style={styles.tooltipRow}>
                 <Text style={styles.tooltipText}>Add project</Text>
-                <Shortcut keys={["⌘", "⇧", "O"]} />
+                {newAgentKeys ? <Shortcut keys={newAgentKeys} /> : null}
               </View>
             </TooltipContent>
           </Tooltip>