feat: add server online history tab with date-grouped chip wall (#97)

* feat(server-detail): add online history tab

Render per-server online periods from GET /api/v1/server/:id/online-history:
summary card (current status, online rate, total in window, last active),
daily online-time bars, and the raw period list. Window selector offers
1d/7d/30d and locks options beyond the server's max_days; guests hitting
the 1d cap see a login hint. i18n keys added for all locales (zh-CN/zh-TW
translated, others fall back to English for Weblate).

* fix(online-history): keep selector pills above the sliding indicator

The active-indicator overlay sits at z-10 and intercepted clicks on the
day pills; wrap pills at z-20 like the existing PeriodSelector.

* feat(online-history): render daily online as 24h timeline with hover tooltips

每日在线卡片从整日占比进度条改为 0:00–24:00 整轴时间条：
每个在线时段按当日时刻定位为高亮分段，hover 显示起止时间与时长；
进行中时段以亮色高亮。卡片顶部新增共享刻度（0:00 / 12:00 / 24:00）。

* feat(online-history): regroup periods by day as expandable chip wall

Rework the Online tab per the chip-wall design: periods are grouped by
panel-timezone day with per-day totals, defaulting to the latest day with
"Expand more" revealing up to ten more groups per click, plus an
Online/Offline switch that derives offline chips as the window complement.

- respond to the backend panel timezone (timezone/tz_offset): dayjs 1.11
  .tz(input, zone) ignores explicit offsets, so offset-bearing timestamps
  are parsed first and converted afterwards; naive date strings keep the
  zone-parse path (panelDay)
- guests falling back automatically: a rejected days>1 request locks 7d/30d
  and retries at 1d instead of surfacing only a login prompt
- fix day-selector indicator landing on the wrong pill: useActiveIndicator
  refs are stored by index, pass the map index not the day value
- disable Node experimental webstorage in vitest workers: Node >=25 ships a
  broken global localStorage that shadows the jsdom one
- 14 locales: tabSwitch.Online + serverOnlineHistory.*

* feat(online-history): boxed summary stats with desktop/mobile layouts

* fix(online-history): align offline gaps, DST coordinates and ongoing chips

- extract pure timeline/grouping helpers into src/lib/online-history.ts
- clamp offline complements to day and window boundaries, so a gap can no
  longer run into a later day's first online session
- use wall-clock coordinates and true next-midnight boundaries on DST days
- label only the segment ending at the live session end as Ongoing
- keep group totals equal to the visible chips for cross-day sessions
- keep period chips on one line and render next-midnight as 24:00
- add regression tests for multi-day offline gaps, window_start/window_end,
  spring-forward/fall-back geometry and ongoing clipping

* style(online-history): lighten summary metrics and shorten rate bar

* feat(online-history): refine UI and unify daily history rendering

---------

Co-authored-by: Sam5440 <Sam5440@users.noreply.github.com>
Co-authored-by: hamster1963 <1410514192@qq.com>

src/locales/uk/translation.json

@@ -69,5 +69,26 @@
 		"today": "Сьогодні",
 		"loading": "Завантаження..."
 	},
-	"login": "Логін"
+	"login": "Логін",
+	"tabSwitch": {
+		"Online": "Online"
+	},
+	"serverOnlineHistory": {
+		"days1": "1d",
+		"days7": "7d",
+		"days30": "30d",
+		"onlineRate": "Online rate",
+		"totalOnline": "Online in window",
+		"lastActive": "Last active",
+		"dailyOnline": "Daily online time",
+		"periods": "Online periods",
+		"ongoing": "Ongoing",
+		"noData": "No online records",
+		"loginRequired": "This window requires login; guests can switch to 1d",
+		"offlinePeriods": "Offline periods",
+		"periodsOnline": "Online",
+		"periodsOffline": "Offline",
+		"expandMore": "Expand more",
+		"today": "Today"
+	}
 }