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.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"os"
 	"os/exec"
+	"regexp"
 	"strings"
 	"time"
 
@@ -556,9 +557,19 @@ func (t *Tmux) IsAgentRunning(session string, expectedPaneCommands ...string) bo
 
 // IsClaudeRunning checks if Claude appears to be running in the session.
 // Only trusts the pane command - UI markers in scrollback cause false positives.
+// Claude can report as "node", "claude", or a version number like "2.0.76".
 func (t *Tmux) IsClaudeRunning(session string) bool {
-	// Claude runs as node
-	return t.IsAgentRunning(session, "node")
+	// Check for known command names first
+	if t.IsAgentRunning(session, "node", "claude") {
+		return true
+	}
+	// Check for version pattern (e.g., "2.0.76") - Claude Code shows version as pane command
+	cmd, err := t.GetPaneCommand(session)
+	if err != nil {
+		return false
+	}
+	matched, _ := regexp.MatchString(`^\d+\.\d+\.\d+`, cmd)
+	return matched
 }
 
 // WaitForCommand polls until the pane is NOT running one of the excluded commands.