Remove IPs page auto-refresh; clear checkboxes after bulk recheck

The 5s auto-refresh (ec44d54) and the hx-sync fix on top of it (5a53705)
didn't resolve the issues seen in manual testing. Rather than keep
debugging htmx's polling/preserve/sync interaction, drop auto-refresh
entirely: handleIPsFragment, GET /ips/fragment, and the poll
attributes/PollSeconds plumbing are all removed. The table now only
updates when a button action re-renders it, as it did before auto-refresh
was added — the bulk-recheck feature itself (handleIPsRecheckSelected,
POST /ips/recheck, "Перепроверить выбранные") is untouched.

Also drops hx-preserve/id from the row checkboxes: it existed solely to
survive the auto-poll wiping a selection mid-task, so it has no purpose
left, and it was actively wrong for one case — after a successful
"Перепроверить выбранные", it kept the just-submitted addresses checked
instead of clearing them. Since the checkbox's checked state was never
server-rendered to begin with, removing hx-preserve alone makes every
table swap (including the recheck button's own) render fresh, unchecked
boxes, which is exactly the desired "selection clears once the action has
been applied" behavior.

Left hx-sync="#ips-table-wrap:queue last" on the action buttons/form —
still cheap protection against a double-click race between two real user
actions, independent of the now-removed polling.

Rebuilt bin/admin-dashboard and bin/SHA256SUMS per docs/SETUP.md.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

bin/SHA256SUMS

@@ -1,4 +1,4 @@
 dcb137ae6a3f6a59465f2772215d48f98fd303dd1c266645b20ec70194ab7915  control-api
 b7a6068db1d095ae7b73cbd9b7273d6a1629ae017e9c3c9601e103432894a247  validator-agent
 be8e9576c6fbe5e5798b5d4b758a5617b63bea6abe80e326998d10583edbbf5c  prober
-cec482fb92246210108261cfc02c10ef9829ce3c7d7c174cf935976baa42fd2c  admin-dashboard
+61d1df7aa84528e8fd9b5e700ac6a9b77e45763b5c5d938913dbce25d0ad9940  admin-dashboard