frank-primary + frank-large: export /metrics, raise primary log verbosity to 4

Both b11030 serve scripts never passed --metrics, so /metrics answered
501 and Prometheus could not scrape frank-large (silently down since
its deploy) or frank-primary. frank-primary also gets -lv 4 (VERBOSITY
env tunable, default 4) for the full per-buffer load breakdown.

scripts/serve-frank-large.sh

@@ -81,6 +81,7 @@ ARGS=(
     --parallel "$PARALLEL_SLOTS"
     --n-gpu-layers 999
     --jinja
+    --metrics
     --chat-template-file "$TEMPLATE_FILE"
     --chat-template-kwargs '{"preserve_thinking":true}'
     --cache-type-k q8_0