fix: send Ctrl+L after tab switch to clear stale Ink CUP frames

Tailed terminal buffers contain multiple CUP-positioned Ink frames from
different time points. When replayed in xterm, old frames at viewport
positions not covered by the latest frame persist as ghost content
(e.g. duplicate "bypass permissions" bars). After buffer load, send
Ctrl+L via the session input API to trigger a full Ink redraw, which
overwrites all stale frame content with the correct current state.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/web/public/app.js

@@ -2240,9 +2240,19 @@ class CodemanApp {
         });
       }
 
-      // Fire-and-forget resize — don't await to avoid blocking UI.
-      // The resize triggers an Ink redraw in Claude which streams back via SSE.
-      this.sendResize(sessionId);
+      // Fire-and-forget resize + Ctrl+L to force Ink redraw.
+      // Tailed buffers accumulate stale CUP-positioned Ink frames that overlap
+      // in the viewport (e.g. duplicate "bypass permissions" bars). Ctrl+L
+      // triggers a full Ink redraw which overwrites all stale frame content.
+      // sendResize may be a no-op if dimensions match, so Ctrl+L is essential.
+      this.sendResize(sessionId).then(() => {
+        if (selectGen !== this._selectGeneration) return;
+        fetch(`/api/sessions/${sessionId}/input`, {
+          method: 'POST',
+          headers: { 'Content-Type': 'application/json' },
+          body: JSON.stringify({ input: '\x0c' })
+        }).catch(() => {});
+      });
 
       // Defer secondary panel updates so they don't block the main thread
       // after terminal content is already visible.