fleetd #365: the push-nudge metric outcome is 'sent', not 'delivered'

The label was renamed in the #365 merge. This table still named the old one.
'sent' counts the herdr paste-and-submit call returning, never a confirmation
that the pane read it.

docs/CB-5xx-Hardening.md

@@ -192,7 +192,7 @@ Deliberately small; every one maps to a failure mode we have actually hit.
 | `fleet_send_duration_seconds` | histogram | delegated turn latency |
 | `fleet_replies_total{path}` | counter | path ∈ rendezvous\|inbox — how often a reply strands (CB-307's whole reason to exist) |
 | `fleet_inbox_depth{target}` | gauge | undrained replies; steady-state should be 0 |
-| `fleet_push_nudges_total{outcome}` | counter | outcome ∈ delivered\|exhausted — a rising `exhausted` means the primary is not draining |
+| `fleet_push_nudges_total{outcome}` | counter | outcome ∈ sent\|exhausted — a rising `exhausted` means the primary is not draining. `sent` was called `delivered` until fleetd #365; it counts the herdr paste-and-submit call returning, never a confirmation the pane read it |
 | `fleet_spawns_total{kind,outcome}` | counter | outcome ∈ ready\|timeout\|guard_rejected; per peer kind (CB-402) |
 | `fleet_sessions{state}` | gauge | SPAWNING/READY/BUSY/DONE census |
 | `fleet_herdr_calls_total{method,outcome}` | counter | socket health — the dependency everything rests on |