fix(dispatcher): send a lone Enter after the task paste to submit it

Multi-line task bodies arrived in Claude Code as "[Pasted text #N +M lines]"
and sat in the input buffer forever — the trailing Enter that SendKeys
appends to the paste is consumed as a newline inside the paste, not as a
submit. Observed live on ccl-auto-11 (secumon) and ccl-auto-12 (secuops):
prompt visible, agent idle.

- tmux.Client grows a SendEnter(session) method. ExecClient runs
  `tmux send-keys -t <sess> Enter` (no preceding text), which Claude's
  TUI accepts as the explicit submit action after a paste.
- Dispatcher: after SendKeys(msg), sleep 500ms for the paste to register,
  then SendEnter. Same sequence a human would perform.
- Five mockTmux implementations updated (quota, dispatcher, switcher,
  lifecycle, watcher tests).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

internal/dispatcher/dispatcher.go

@@ -234,11 +234,19 @@ func (d *Dispatcher) launchAgent(session, projectDir, taskFile string) error {
 		return fmt.Errorf("claude not ready in %q after %v", session, promptTimeout)
 	}
 
-	// Send the task message.
+	// Send the task message. Multi-line task bodies render in Claude's TUI
+	// as "[Pasted text #N +M lines]" — the trailing Enter that SendKeys
+	// appends is consumed as part of the paste, so the message would stay
+	// unsubmitted in the input buffer forever. Wait for the paste to
+	// register, then send a lone Enter to actually submit.
 	msg := buildTaskMessage(body, taskFile)
 	if err := d.tmux.SendKeys(session, msg); err != nil {
 		return err
 	}
+	time.Sleep(500 * time.Millisecond)
+	if err := d.tmux.SendEnter(session); err != nil {
+		return err
+	}
 
 	d.state.SetWorking(session, filepath.Base(taskFile))
 	d.logger.Printf("[dispatcher] DISPATCHED session=%q task=%s model=%s",

internal/dispatcher/dispatcher_test.go

@@ -31,6 +31,10 @@ func (m *mockTmux) SendKeys(_, keys string) error {
 	m.sentKeys = append(m.sentKeys, keys)
 	return nil
 }
+func (m *mockTmux) SendEnter(_ string) error {
+	m.sentKeys = append(m.sentKeys, "<ENTER>")
+	return nil
+}
 func (m *mockTmux) CapturePaneTail(session string, _ int) (string, error) {
 	return m.paneOutput[session], nil
 }