prometheus: drop the frank-primary scrape job (FreeToken exports no /metrics)

FreeToken has no /metrics endpoint — the job scraped 404s forever, a
structural never-green, not an outage (the Lucebox DS4.1 precedent). The
LlmEndpointDown alert regex self-adjusts (frank-.* matches existing series
only). Comments updated; seam now asserts frank-primary's absence. If
FreeToken grows /metrics, re-add the job.

shared/prometheus/rules/llm-fleet.yml

@@ -1,10 +1,12 @@
 # Alerting and recording rules for the LLM fleet.
 #
-# One metric namespace: llamacpp:* — frank-small, frank-large and
-# frank-primary, all llama.cpp with /metrics (the family verified from
-# /metrics on 2026-09-16 and 2026-09-20). frank-primary is scraped across
-# the LAN at 192.168.0.235:7770 (the netavark published-port quirk that
-# forces the gateway for the Dankclaw endpoints is same-host only).
+# One metric namespace: llamacpp:* — frank-small and frank-large, both
+# llama.cpp with /metrics (the family verified from /metrics on 2026-09-16
+# and 2026-09-20). frank-primary LEFT the family 2026-10-05: FreeToken (the
+# PR587 ROCm engine) has no /metrics endpoint, so its scrape job was
+# deleted rather than left never-green.
+# (The netavark published-port quirk that forces the Dankclaw endpoints
+# onto the gateway is same-host only.)
 #
 # Every expression is keyed to a series that EXISTS. Nothing matches on
 # absence: when an endpoint's runtime leaves the fleet, its selectors are
@@ -110,6 +112,6 @@ groups:
           description: >-
             Prometheus cannot reach the LLM endpoint. frank-small and
             frank-large are root units on Dankclaw: `systemctl is-active
-            frank-small` / `frank-large`. frank-primary is a root unit on
-            Dankserver: `systemctl is-active frank-primary`. All three
-            scraped endpoints export the llamacpp:* family.
+            frank-small` / `frank-large`. Both scraped endpoints export
+            the llamacpp:* family. (frank-primary left the scrape set
+            2026-10-05 — FreeToken exports no /metrics.)