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/prometheus.yml

@@ -98,10 +98,12 @@ scrape_configs:
   # service down. Same host, same rule, so both local endpoints use the
   # gateway.
   #
-  # (2026-09-26) frank-primary is llama.cpp again (the unsloth b11030-mix
-  # prebuilt serving Qwen3.8-Flash-Next Q8_0) on Dankserver, a DIFFERENT
-  # machine: the netavark published-port quirk above is same-host only, so
-  # plain LAN routing reaches 192.168.0.235:7770 and the job returns.
+  # (2026-10-05) frank-primary left this file: FreeToken (the PR587 ROCm
+  # engine now serving it) has NO /metrics endpoint — the job scraped 404s
+  # forever, which is a structural never-green, not an outage. The
+  # netavark published-port quirk above is same-host only; plain LAN
+  # routing REACHES 192.168.0.235:7770 (health answers) — only the metrics
+  # path is absent. If FreeToken grows a /metrics, re-add the job here.
   - job_name: "frank-small"
     metrics_path: "/metrics"
     static_configs:
@@ -116,9 +118,3 @@ scrape_configs:
         labels:
           service: frank-large
 
-  - job_name: "frank-primary"
-    metrics_path: "/metrics"
-    static_configs:
-      - targets: ["192.168.0.235:7770"]
-        labels:
-          service: frank-primary