fix(statusline): print nothing instead of the bare word codeman

Ported from #416 (discussion #405): a statusline reading just `codeman`
is what a hand-run claude in a managed repo showed, and it reads as a
broken config rather than a footer. Three paths produced it and all
three now yield an empty footer: the exporter's `|| echo codeman`
fallback (now `curl -sfk ... || true`, with -f keeping an HTTP error
body off stdout), the unknown-session answer of POST /api/status-telemetry,
and formatSessionStatusText() with nothing to show. The exporter script
marker moves to V4 so live installs pick the new content up on the next
spawn.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

src/web/routes/status-telemetry-routes.ts

@@ -8,8 +8,9 @@
  * (localhost-only; hook-secret-gated while a tunnel runs — see middleware/auth).
  *
  * Returns a compact plain-text status string for the exporter to print as the
- * in-terminal footer (print-through), so injecting our statusLine doesn't leave
- * the terminal footer blank.
+ * in-terminal footer (print-through) when it has no statusline of the user's
+ * own to wrap. An unknown session gets an EMPTY body: the old brand-word
+ * answer rendered as the statusline itself (discussion #405).
  */
 
 import { FastifyInstance } from 'fastify';
@@ -36,10 +37,11 @@ export function registerStatusTelemetryRoutes(app: FastifyInstance, ctx: Session
 
     reply.type('text/plain; charset=utf-8');
 
-    // Unknown session — minimal footer, no broadcast.
+    // Unknown session: nothing to broadcast and nothing to print. Never a brand
+    // word here, it would render as the statusline.
     if (!ctx.sessions.has(sessionId)) {
       lastSig.delete(sessionId);
-      return 'codeman';
+      return '';
     }
 
     const payload = data as RawStatuslinePayload | undefined;