Sign the completion and the probe with the same token (V-673)

llm.Client carries a bearer credential and sets it on the completion, and
Pair signs the /health probe with it too. An unsigned probe would answer 401,
Pair would read that as a card that is busy, and every workstation turn would
fall back to the resident model with nothing naming why.

The token comes from workstation.token, expanded from MAVEN_GPU_TOKEN like
every other secret in that file. Missing, and voicewire says so at startup:
the fallback is silent by design and this failure would otherwise be
invisible.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ESv8hqNPseYt1CnotZpqDz

deploy/telegram.env.example

@@ -10,3 +10,12 @@ TELEGRAM_CHAT_ID=
 #   ntfy token add --expires=never maven
 # Read access is not needed — mavend publishes and never subscribes.
 NTFY_TOKEN=
+
+# Bearer token for mavgpud, the workstation's GPU supervisor (V-673). It fronts
+# the big model on a LAN port, so the token is the whole boundary in front of
+# the card. Any long random string; mint one with:
+#   openssl rand -hex 32
+# The same value goes in a file on workpc, named by token_file in
+# deploy/mavgpud.json. Unset here and every workstation turn falls back to the
+# resident model, because mavgpud answers 401 and Maven reads that as down.
+MAVEN_GPU_TOKEN=