fix(reaper): deliver pre-reap warnings for real — and never fake a delivery

The §18 warning path had no delivery channel at all: no Warner implementation
existed, `felis reaper` passed nil, and maybeWarn still stamped warned_3d_at/
warned_1d_at and counted `warned=N`. So every owned server was silently reaped
15 days after its last join with no notice, and the operator's only feedback
said warnings were sent. Two changes close that:

- Honest stamps: warned_* now records a DELIVERED notice. A nil Warner logs
  `warning suppressed — no warner wired` and does NOT stamp; a delivery error
  logs and retries on the next daily run (bounded by the warning window). The
  stamps are no longer burned by notices nobody received.

- A real channel: mail.SendNotice (the second and last message shape the mail
  package sends) plus a mailWarner that resolves the owner's VERIFIED email
  and mails the notice through the configured [smtp] relay. `felis reaper`
  wires it when [smtp] is set (same password_ref convention as felis-api) and
  prints exactly what happens when it is not.

Plumbing so the in-cluster CronJob can actually reach the relay: the reaper
pod gets the optional FELIS_SMTP_PASSWORD env (same Secret as felis-api), and
the "configure email" screen now refreshes the minecraft-namespace mirrors of
felis-smtp AND felis-config (a secretKeyRef is namespace-local, and the config
mirror is what carries [smtp] into the reaper's own config). `felis setup`'s
replica list gains felis-smtp for fresh installs.

Tests: the delivered/retried/suppressed matrix in internal/reaper (the old
"stamp advances on failure" contract is deliberately replaced), the notice
message shape, the warner's resolve/send/failure paths, and the CronJob's
optional-secret env. docs/troubleshooting.md §10 now states the real semantics.

cmd/felis/setup.go

@@ -246,6 +246,13 @@ func provisionSystemServers(ctx context.Context, cfg *config.Config, out io.Writ
 			naming.ForwardingSecretName, naming.ForwardingSecretKey, "forwarding-secret", "minecraft ns"),
 		ensureSecretReplica(ctx, cl, controlNS, cfg.K8s.Namespace,
 			"felis-config", "felis.toml", "config", "minecraft ns"),
+		// The reaper's pre-reap warning emails authenticate with the same relay
+		// password felis-api uses; the reaper pod runs in the minecraft namespace,
+		// where a secretKeyRef resolves only against a local mirror. Skipped while
+		// the relay is not configured yet — the "configure email" screen refreshes
+		// both mirrors when it applies.
+		ensureSecretReplica(ctx, cl, controlNS, cfg.K8s.Namespace,
+			"felis-smtp", "password", "smtp", "minecraft ns"),
 		// The build namespace needs the same token: the build Job's fetch
 		// initContainer reads the submission context from the internal face. Best
 		// effort — a deployment that only installs the control plane simply never