fix: session restoration now properly attaches to existing screens

- Pass existing screenSession to Session constructor for restored sessions
- Skip terminal buffer clearing when attaching to restored (existing) screens
- Frontend auto-calls /interactive endpoint when selecting a restored session
- Fixes issue where restored sessions appeared broken after server restart

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

src/web/server.ts

@@ -1393,14 +1393,15 @@ export class WebServer extends EventEmitter {
         const screens = this.screenManager.getScreens();
         for (const screen of screens) {
           if (!this.sessions.has(screen.sessionId)) {
-            // Create a session object for this screen
+            // Create a session object for this screen with the existing screenSession
             const session = new Session({
               id: screen.sessionId,  // Preserve the original session ID
               workingDir: screen.workingDir,
               mode: screen.mode,
               name: screen.name || screen.screenName,
               screenManager: this.screenManager,
-              useScreen: true
+              useScreen: true,
+              screenSession: screen  // Pass the existing screen so startInteractive() can attach to it
             });
 
             this.sessions.set(session.id, session);