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

internal/llm/client.go

@@ -51,6 +51,10 @@ type Client struct {
 	base string
 	swap SwapGate
 	http *http.Client
+	// token — the bearer credential for a server that asks for one. Empty for
+	// the resident model, which is reached over loopback on the same box.
+	// mavgpud on the workstation requires it: that hop is on the LAN.
+	token string
 
 	// gate / background — priority on the single llama-server slot. Set once
 	// at wiring time (SetGate), read on every request. nil gate ⇒ no gating,
@@ -101,6 +105,27 @@ func New(baseURL string, timeout time.Duration) *Client {
 	return &Client{base: baseURL, http: &http.Client{Timeout: timeout}}
 }
 
+// SetToken installs the bearer credential this client sends. Wiring-time, like
+// SetGate: an empty token means the server is not asking for one.
+func (c *Client) SetToken(t string) {
+	c.mu.Lock()
+	c.token = t
+	c.mu.Unlock()
+}
+
+// authorize adds the credential when there is one. Exported to the package so
+// the Pair prober signs /health with the same token as the completion — a
+// probe that answers 401 would otherwise read as a workstation that is down,
+// and Maven would fall back forever without saying why.
+func (c *Client) authorize(req *http.Request) {
+	c.mu.RLock()
+	t := c.token
+	c.mu.RUnlock()
+	if t != "" {
+		req.Header.Set("Authorization", "Bearer "+t)
+	}
+}
+
 // SetBaseURL re-points the client at another llama-server. Safe to call while
 // requests are in flight: a request that already read the old base finishes
 // against the old base (or fails, and every caller of Complete has a fallback),
@@ -196,6 +221,7 @@ func (c *Client) Complete(ctx context.Context, r Req) (string, error) {
 		return "", err
 	}
 	req.Header.Set("Content-Type", "application/json")
+	c.authorize(req)
 	httpResp, err := c.http.Do(req)
 	if err != nil {
 		return "", err