v0.121.1: 'nothing is due' must be AUDIBLE (R-86 + standing rule 3)

Before R-86 every tick ran a heavy restore-test, so the scheduler was audible by
construction. After it, 'nothing is due' is the NORMAL outcome — and it was
logged at DEBUG, which journald drops. An empty journal would then be equally
consistent with a healthy loop and a dead goroutine: the shape the R-88 watcher
was retired for, re-created by making the quiet path the common one.

A not-due evaluation now logs one INFO line naming every tier's verdict (four
lines a day at the 6h default), and an unlistable tier reads UNKNOWN with its
error in that same line, so a lookup failure can never present as 'nothing due'.

Red-proved through the scheduler's own tick, not the helper.

CHANGELOG.md

@@ -1,3 +1,28 @@
+## v0.121.1 — "nothing is due" must be AUDIBLE (2026-08-03, R-86 + standing rule 3)
+
+**Found while live-validating v0.121.0, and it is this project's own rule pointed at the change that
+had just shipped.** Before R-86 every tick ran a heavy restore-test, so the scheduler was audible by
+construction. After it, *"nothing is due"* is the NORMAL outcome — and it was logged at **DEBUG**,
+which journald drops. An empty journal would then have been equally consistent with a healthy loop
+and with a dead goroutine: the exact shape the R-88 watcher was retired for, re-created in a new
+place by making the quiet path the common one.
+
+A not-due evaluation now logs one **INFO** line naming every tier's verdict:
+
+```
+backup: restore-test evaluated — nothing due
+  verdicts="felhom-pbs: newest settled archive (landed 2026-07-28T04:49:43Z) is already proven;
+            felhom-backup: no settled archive yet — nothing to prove (newborn or still settling)"
+```
+
+Four lines a day at the 6 h default, and the answer to *"why did nothing run last night?"* is in the
+log instead of being re-derived. A tier whose storage cannot be listed reads `UNKNOWN` with its error
+in the same line, so a lookup failure can never present as "nothing due".
+
+Red-proved by reverting to the bare `Debug` line: the test asserts what the SCHEDULER emits on a real
+`tick`, not what the helper returns — a helper-level test would have passed against a tick that never
+called it.
+
 ## v0.121.0 — a restore-test proves each BACKUP, not the clock (2026-08-03, R-86)
 
 **The trigger changed; the restore-test did not.** `Scheduler.Run` still has a ticker, but it is now