Signals' metrics by person and whose key paid (#278)

With the server paying for everyone's Signals, its bill had no names.
ipx_signals_judged_total, ipx_signals_hits_total and ipx_jev_tokens_total
now carry user (the account's name) and key (server or own); a call
shared on the server's key is split by each person's share of its
questions. Icon picks bill the person on the server's key, key checks on
their own. The dashboard has tokens and items by person and a Who used
what table over its range.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.claude/skills/ipx-prod-check/SKILL.md

@@ -109,9 +109,9 @@ from 2026-10-11 15:15 UTC. All gauges:
 | `ipx_feed_retries` | feeds waiting to retry a failed name lookup |
 | `ipx_art_cache_bytes`, `ipx_art_cache_limit_bytes` | artwork kept, as of the last sweep, and the most kept: kept sits at the limit by design |
 | `ipx_art_evicted_total`, `ipx_art_requests_total{result="hit"\|"miss"}` | counters: images the sweep threw out to stay under the limit, and artwork served from disk or fetched from the publisher; many evicted at every sweep with a falling hit rate means the limit is too small |
-| `ipx_signals_judged_total`, `ipx_signals_hits_total` | counters: items Jev judged for Signals, and Signals they fit (#254) |
+| `ipx_signals_judged_total{user,key}`, `ipx_signals_hits_total{user,key}` | counters: items Jev judged for Signals, and Signals they fit, by person and whose key paid (`server` or `own`, #278) (#254) |
 | `ipx_jev_requests_total{result="ok"\|"key_refused"\|"malformed"\|"rate_limited"\|"error"}`, `ipx_jev_seconds_total`, `ipx_jev_paced_seconds_total` | counters: calls to TypeSafe's Jev, Signals' and icons', by how they ended; their seconds, the wait for a turn included; and that wait alone. `malformed` is ipx's request at fault (#257); `rate_limited` is a 429 from TypeSafe, whose limits are 80 calls and 100,000 input tokens a second, which ipx paces itself under at 60 and 80,000 (#277) |
-| `ipx_jev_tokens_total{kind="input"\|"output"}` | counter: tokens TypeSafe counted, as its answers say: what Signals cost (#275) |
+| `ipx_jev_tokens_total{kind="input"\|"output",user,key}` | counter: tokens TypeSafe counted, as its answers say, by person and whose key paid: what Signals, icon picks and key checks cost (#275, #278). A call shared on the server's key is split by each person's share of its questions |
 | `ipx_signals_last_pass_age_seconds`, `ipx_signals_keys_refused` | since the Signals judge last finished a pass (at most 5 minutes when well; absent until one has); people whose key TypeSafe refused |
 | `directory_process_resident_bytes`, `directory_process_open_fds`, `directory_feed_fetches_total`, `directory_feed_bytes_total`, `directory_uptime_seconds`, `directory_build_info` | the directory's, `job="ipx-directory"`, from its `metrics_bind` (production `192.168.1.130:9188`, LAN only) |
 | `ipx_feeds`, `ipx_downloads_pending`, `ipx_files_downloaded` | the library, as the healthcheck last counted it (every 30 s) |