fix(latest,web): finish the atomic deletion and honest empty states (#145)

Review fixes on top of cb2b104:
- Delete the write-only in-memory refuseUntil map and setRefusalBackoff now
  that status.go is gone: the pass gate reads the durable stamp, so the map
  was half-deleted dead state (spec review C-1).
- An outcome-query failure no longer blanks the Lane table into the false
  'no data yet': rows render with 'none observed' chips instead (I-1).
- due-query and eligible-count skips get their own sentences instead of the
  merged 'check failed' (I-2).
- ADR-0012 constrain wording corrected and trailing newline added (M-1)

docs/adr/0012-persisted-lane-state.md

@@ -39,6 +39,6 @@ confident zero.
 The poller still owns the writes: each pass exit records one row (ADR-0010),
 and a pass that returns before gathering figures carries the previous pass's
 numbers forward instead of recording zeroes. A skip is a stable wire string;
-`asleep` never counts toward `Attention`. When polling is switched off the
-page must say so, and the browser statusline appears only when a poller
-actually answers.
+`asleep` never counts toward `Attention`. When polling is switched off
+(`LATEST_CHAPTER_POLL_ENABLED` unset) the page must say so, and the browser
+statusline appears only when polling is switched on.