fix: IsClaudeRunning detects 'claude' and version patterns

Claude Code can report its pane command as "node", "claude", or a version
number like "2.0.76". Previously only "node" was detected, causing healthy
sessions to be incorrectly identified as zombies and killed during daemon
heartbeat recovery.

This fix detects all three patterns to prevent witness sessions from being
killed every 3 minutes.

Based on michaellady's work in PR #174.

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

internal/tmux/tmux_test.go

@@ -2,6 +2,7 @@ package tmux
 
 import (
 	"os/exec"
+	"regexp"
 	"strings"
 	"testing"
 )
@@ -417,11 +418,45 @@ func TestIsClaudeRunning(t *testing.T) {
 	}
 	defer func() { _ = tm.KillSession(sessionName) }()
 
-	// IsClaudeRunning should be false (shell is running, not node)
+	// IsClaudeRunning should be false (shell is running, not node/claude)
 	cmd, _ := tm.GetPaneCommand(sessionName)
-	wantRunning := cmd == "node"
+	wantRunning := cmd == "node" || cmd == "claude"
 
 	if got := tm.IsClaudeRunning(sessionName); got != wantRunning {
 		t.Errorf("IsClaudeRunning() = %v, want %v (pane cmd: %q)", got, wantRunning, cmd)
 	}
 }
+
+func TestIsClaudeRunning_VersionPattern(t *testing.T) {
+	// Test the version pattern regex matching directly
+	// Since we can't easily mock the pane command, test the pattern logic
+	tests := []struct {
+		cmd  string
+		want bool
+	}{
+		{"node", true},
+		{"claude", true},
+		{"2.0.76", true},
+		{"1.2.3", true},
+		{"10.20.30", true},
+		{"bash", false},
+		{"zsh", false},
+		{"", false},
+		{"v2.0.76", false}, // version with 'v' prefix shouldn't match
+		{"2.0", false},     // incomplete version
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.cmd, func(t *testing.T) {
+			// Check if it matches node/claude directly
+			isKnownCmd := tt.cmd == "node" || tt.cmd == "claude"
+			// Check version pattern
+			matched, _ := regexp.MatchString(`^\d+\.\d+\.\d+`, tt.cmd)
+
+			got := isKnownCmd || matched
+			if got != tt.want {
+				t.Errorf("IsClaudeRunning logic for %q = %v, want %v", tt.cmd, got, tt.want)
+			}
+		})
+	}
+}