refactor(heartbeat): remove unreachable else-branch in buildAdapterLivenessLostMessage

The staleThresholdMs <= 0 fallback was dead code — the sole call site
already guards with `if (staleThresholdMs <= 0) continue` before
invoking this function, so staleThresholdMs is always positive.

Addresses Greptile P2 finding on PR paperclipai#4162.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

Author: 2 people

server/src/services/heartbeat.ts

@@ -1569,11 +1569,8 @@ function adapterHasOutOfProcessLiveness(adapterType: string) {
 }
 
 function buildAdapterLivenessLostMessage(adapterType: string, staleThresholdMs: number) {
-  if (staleThresholdMs > 0) {
-    const staleSec = Math.round(staleThresholdMs / 1000);
-    return `Adapter ${adapterType} liveness lost -- no run activity for over ${staleSec}s (out-of-process adapter; local pid not applicable)`;
-  }
-  return `Adapter ${adapterType} liveness lost -- no run activity (out-of-process adapter; local pid not applicable)`;
+  const staleSec = Math.round(staleThresholdMs / 1000);
+  return `Adapter ${adapterType} liveness lost -- no run activity for over ${staleSec}s (out-of-process adapter; local pid not applicable)`;
 }
 
 // A positive liveness check means some process currently owns the PID.