Interval change keeps unreported samples for the reporter (closes #124)

The interval menu cleared every host's history, and the reporter builds
each report from that history, so the samples recorded since the last
delivered report were never sent. The menu now calls
HostState.clearHistory, which moves the history's entries to
clearedHistory, keeping the last maxHistoryPoints as the history does;
buildReport reads both. The per-host marks are unchanged, so a sample a
delivered report had is not sent again, and the page's history still
starts over. Reporter is exported for the new unit test.

Model: opus-5-5

TODO.md

@@ -22,6 +22,16 @@ Decide whether the repo moves to the layout `REPO_POLICIES.md` gives, with
 
 # Completed Steps
 
+- 2026-10-14: changing the interval no longer drops the samples not yet reported
+  to the backend ([#124](https://git.eeqj.de/sneak/netwatch/issues/124)). The
+  interval menu calls the new `HostState.clearHistory`, which moves the
+  history's entries to `clearedHistory`, keeping the last 100 as the history
+  does, and `buildReport` reads both, so the next report has the samples
+  recorded before the change that no report has delivered. The page's history
+  still starts over, and the per-host marks still leave out of a report the
+  samples a delivered one had. A unit test sends a report, records samples,
+  clears the history as the interval menu does and finds them in the next
+  report; `src/main.js` now exports `Reporter` for it
 - 2026-10-07: the files shared from `sneak/prompts` are its copies at commit
   `dd4027b` ([#113](https://git.eeqj.de/sneak/netwatch/issues/113)), with this
   repository's own entries after the shared content in `.gitignore`,