Add optional automatic check cycle (clear queue -> scan FIPs -> wait -> repeat)

An admin-controlled scenario that repeats what the operator does by hand:
clear the IP queue, scan and enqueue all free Floating IPs, wait until every
queued address reaches a terminal state (so results are in the Registry),
then wait a configurable interval and start over.

- control-api: new auto_cycle singleton table (migration 0008) holding
  enabled/interval/max-run settings and persisted phase state, so the cycle
  survives restarts; engine in orchestrator/autocycle.go driven from the
  existing loop tick with an injectable "now" for deterministic tests.
- Interval (default 1h, min 60s) and max wait (default unlimited, timeout
  outcome) are runtime settings, never hardcoded.
- The periodic fip_scan_interval_seconds scan is skipped while the cycle is
  enabled. An emptied queue mid-cycle counts as finished; stopping during
  the pause keeps the last cycle's outcome.
- API: GET/PUT /api/v1/admin/auto-cycle, POST .../start, POST .../stop.
- admin-dashboard: "Автоматический цикл" panel on /settings and an
  "Автоцикл активен" indicator on /overview.
- Tests for db, orchestrator, httpapi and dashboard; run-local-e2e.sh now
  exercises a full auto cycle; docs updated; bin/ rebuilt with refreshed
  SHA256SUMS.

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

internal/dashboard/templates/overview_fragment.html

@@ -6,6 +6,9 @@
 <div class="stat-card{{if eq $state "failed"}} bad{{else if eq $state "checking"}} accented{{end}}"><span class="value">{{$count}}</span><span class="label">{{$state}}</span></div>
 {{end}}
 </div>
+{{with .AutoCycle}}{{if .Enabled}}
+<p class="muted" id="overview-auto-cycle" style="margin-top:12px"><span class="pill pill-info">Автоцикл активен</span> · {{.PhaseLabel}} · следующий запуск: {{fmtTime .NextRunAt}}</p>
+{{end}}{{end}}
 {{end}}
 
 {{/* Out-of-band counterpart of overview_stats, appended to every

internal/dashboard/templates/settings.html

@@ -28,6 +28,47 @@
 {{end}}
 
 {{define "settings_form"}}
+<div class="panel" id="auto-cycle-panel">
+<div class="panel-body">
+<h2 class="section-title" style="margin-top:0">Автоматический цикл</h2>
+<p class="muted" style="margin-bottom:16px">Повторяет сценарий оператора: «Очистить всё» → «Сканировать Floating IP» →
+ожидание, пока все адреса очереди пройдут проверку → пауза и новый цикл. Интервал отсчитывается от завершения
+предыдущего цикла. Пока автоцикл включён, периодическое сканирование по <code>fip_scan_interval_seconds</code>
+не выполняется. Выключение не прерывает проверки, которые уже идут.</p>
+<p style="margin-bottom:16px">
+<span class="pill {{if .AutoCycle.Enabled}}pill-success{{else}}pill-neutral{{end}}">{{if .AutoCycle.Enabled}}Автоцикл включён{{else}}Автоцикл выключен{{end}}</span>
+· фаза: {{.AutoCycle.PhaseLabel}}
+</p>
+<div class="muted" style="margin-bottom:16px">
+<div>Последний запуск: {{fmtTime .AutoCycle.LastRunStartedAt}}</div>
+<div>Завершён: {{fmtTime .AutoCycle.LastRunFinishedAt}}</div>
+<div>Следующий запуск: {{fmtTime .AutoCycle.NextRunAt}}</div>
+<div>Результат последнего цикла: <span class="pill {{.AutoCycle.OutcomePillClass}}">{{.AutoCycle.OutcomeLabel}}</span>{{if .AutoCycle.LastError}} — {{.AutoCycle.LastError}}{{end}}</div>
+<div>Свободных адресов в последнем скане: {{.AutoCycle.LastScannedFree}} · завершённых циклов: {{.AutoCycle.RunsTotal}}</div>
+</div>
+<form hx-put="/settings/auto-cycle" hx-target="#settings-form-wrap" hx-swap="innerHTML">
+<div class="field-row">
+<div class="field">
+<label for="auto_cycle_interval">Интервал между циклами (мин)</label>
+<input type="number" id="auto_cycle_interval" name="interval_minutes" min="1" step="any" value="{{.AutoCycle.IntervalMinutes}}" required>
+</div>
+<div class="field">
+<label for="auto_cycle_max_run">Максимальная длительность проверки (мин, 0 = без лимита)</label>
+<input type="number" id="auto_cycle_max_run" name="max_run_minutes" min="0" step="any" value="{{.AutoCycle.MaxRunMinutes}}" required>
+</div>
+<button type="submit" class="btn btn-primary">Сохранить</button>
+</div>
+</form>
+<div style="margin-top:16px">
+{{if .AutoCycle.Enabled}}
+<button type="button" class="btn btn-primary" hx-post="/settings/auto-cycle/stop" hx-target="#settings-form-wrap" hx-swap="innerHTML">Выключить</button>
+{{else}}
+<button type="button" class="btn btn-primary" hx-post="/settings/auto-cycle/start" hx-target="#settings-form-wrap" hx-swap="innerHTML">Включить</button>
+{{end}}
+</div>
+</div>
+</div>
+
 <div class="panel">
 <div class="panel-body">
 <p class="muted" style="margin-bottom:16px">Пауза между привязкой Floating IP к валидатору и началом self-check —