feat(tui): add Delete All (D) to kill all screens and Claude processes

- Add killAllScreensAndClaude() function to useSessionManager
- Kills all tracked sessions, orphan claudeman screens, and Claude CLI processes
- Press 'D' (Shift+d) in sessions view to trigger
- Update HelpOverlay with new shortcut documentation

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/tui/components/StartScreen.tsx

@@ -30,6 +30,7 @@ interface StartScreenProps {
   onSelectSession: (session: ScreenSession) => void;
   onAttachSession: (session: ScreenSession) => void;
   onDeleteSession: (session: ScreenSession) => void;
+  onDeleteAll: () => void;
   onCreateSession: (caseName?: string, count?: number, mode?: 'claude' | 'shell') => void;
   onCreateCase: (name: string) => Promise<boolean>;
   onRefresh: () => void;
@@ -80,6 +81,7 @@ export function StartScreen({
   onSelectSession,
   onAttachSession,
   onDeleteSession,
+  onDeleteAll,
   onCreateSession,
   onCreateCase,
   onRefresh,
@@ -168,6 +170,12 @@ export function StartScreen({
         return;
       }
 
+      // 'D' (shift+d) to delete ALL screens and Claude processes
+      if (input === 'D') {
+        onDeleteAll();
+        return;
+      }
+
       // 'c' to switch to cases view
       if (input === 'c') {
         onRefreshCases();
@@ -513,6 +521,8 @@ export function StartScreen({
                 <Text> Attach  </Text>
                 <Text color="red">[d]</Text>
                 <Text> Delete  </Text>
+                <Text color="red" bold>[D]</Text>
+                <Text> Delete ALL  </Text>
                 <Text color="yellow">[q]</Text>
                 <Text> Quit</Text>
               </Text>