local-time: the panel in the container's zone, named on Settings

Agreed by the owner on 2026-10-13 (the local day, no "UTC" beside a
time); the zone is the container's TZ in .env and Settings only shows it,
his "Да" of 2026-10-17. Mockups c205106.

Every time the panel shows is formatted in time.Local and says no zone:
the logs' Time and the DMARC Received columns, a message's timeline,
Overview's "Updated", Health's certificate and renewal, the filter lists,
DMARC reports and windows, the auto limit's last recalculation. Stored
instants stay UTC. The days counted are the zone's: delivery_log_days and
sender_check_days key their rows by the local date, the sender check cuts
downtime at local midnights (byDay), the log filters' days run from local
midnight to local midnight. Notification mail and the test message write
the zone's abbreviation after a time - they are read away from the panel.
DMARC's one-day window label stays the reporter's (UTC) day.

Settings box 05, Time zone, read-only: the name (UTC without TZ), its
offset, and a TZ the image cannot load said to leave the times in UTC
(time/zoneinfo_unix.go, initLocal) rather than named. TZ is passed by the
compose file ("${TZ:-}"), in .env.example and the guide's table; tzdata is
named in the image (supervisor's python3.13 brings it today). Postfix
takes TZ through import_environment, so mail.log's stamps are the same
zone, which closes the trap the roadmap wrote down: the tailer has always
read them in time.Local.

Tests: a TestMain runs view, handlers, store and cmd/panel in UTC whatever
the machine's zone (as logtail's); TestSettingsShowsTheTimeZone,
TestTimesAreTheContainersZone, TestByDayInTheContainersZone, a Moscow day
in TestQueryInboundSpamFilters; envdoc's pattern takes two-letter names.
e2e time_zone_is_the_containers recreates the stand with
TZ=Europe/Moscow: date says MSK, Settings names the zone and UTC+03:00, a
test message's page gives its time and its mail.log lines in Moscow's.
go vet + go test (26 packages) and make e2e on the test server for this
tree.

Docs: guide (§ Settings, the TZ row, the days of Health and the logs),
architecture, schema-migrations, help (word for word with the mockup),
CHANGELOG [Unreleased] § Added, roadmap row done with the decision.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/schema-migrations.md

@@ -119,8 +119,8 @@ for operators upgrading from older 2.x images.
 | `inbound_spam_log` | Inbound antispam journal: one row per recipient of a message offered on port 25, with the decision (`accept`, `reject`, `tempfail`, `quarantine`) and who made it (`rspamd`, `postfix`, `selfpost`). Metadata only. `inbound_domain_id` (v8) ties a row to its domain by id (v2) |
 | `inbound_spam_list` | Allow / deny entries for the external filter (`address`, `domain`, `ip`), instance-wide; unique per list (v2) |
 | `notify_state` | What the panel has already written to its users about, one row per subject (`dns:<domain>`, `cert`, `queue`, `limit:<domain>`), so that each thing is said once and a restart says nothing again (v4) |
-| `sender_check_days` | What the sender check costs, a row per UTC day that has something to say: seconds the panel did not answer while Postfix ran, connections turned away (`deferred`), messages deferred mid-message (`messages`), and whether the day's downtime is an upper bound (`estimated`). Kept a year (v6, v9) |
-| `delivery_log_days` | What the reconcile sweep and the log tailer did, a row per UTC day, kept a year. Read off a copy of the database; no page shows it (v7) |
+| `sender_check_days` | What the sender check costs, a row per day of the container's zone (`TZ`) that has something to say: seconds the panel did not answer while Postfix ran, connections turned away (`deferred`), messages deferred mid-message (`messages`), and whether the day's downtime is an upper bound (`estimated`). Kept a year (v6, v9) |
+| `delivery_log_days` | What the reconcile sweep and the log tailer did, a row per day of the container's zone, kept a year. Read off a copy of the database; no page shows it (v7) |
 | `notify_addressees` | Who a subject's notification is owed to and whether each was handed it; goes with the subject's `notify_state` row (v11) |
 | `send_log_lines` | The `mail.log` lines Postfix wrote under a queue id, with the line's own time; what a message's page shows once the log has rotated. No reference to `send_log`: a line belongs to a row by queue id and time, and goes when no row carries its id (v3) |