refactor(dashboard): switch usage charts to route group_by, rename Models card

Align dashboard with the route dimension introduced in the previous
commit:

* Token Usage / API Requests pie charts query the breakdown API with
  `group_by: ['date', 'route']` and aggregate via the new `route`
  dimension in `buildUsageLabel`. Visible chart titles keep the existing
  "by Model" wording — only the underlying data dim changed.
* Overview "Models" card label switched to `dashboard.deployments`
  ("部署" / "Deployments"), and the Active Models table heading to
  `dashboard.activeDeployments`. These reflect the underlying entity
  (model deployments) more accurately now that routes are the
  user-facing model concept.
* Drop 11 unused dashboard locale keys (`dashboard.title`,
  `dashboard.models`, `dashboard.allocategpus`, `dashboard.instances`,
  `dashboard.disk`, `dashboard.diskutilization`, `dashboard.apirequest`,
  `dashboard.activeModels`, `dashboard.activeUsers`,
  `dashboard.activeModels.name`, `dashboard.runninginstances`) — no
  remaining references in `src/` after the rename. Locale parity check
  passes.

src/locales/ja-JP/dashboard.ts

@@ -1,31 +1,22 @@
 export default {
-  'dashboard.title': 'ダッシュボード',
   'dashboard.workers': 'ワーカー',
-  'dashboard.models': 'モデル',
+  'dashboard.deployments': 'Deployments',
   'dashboard.totalgpus': 'GPU数',
-  'dashboard.allocategpus': '割り当て済みGPU',
-  'dashboard.instances': 'インスタンス',
   'dashboard.systemload': 'システム負荷',
   'dashboard.memory': 'メモリ',
-  'dashboard.disk': 'ストレージ',
   'dashboard.vram': 'VRAM',
   'dashboard.cpuutilization': '平均CPU使用率',
   'dashboard.memoryutilization': '平均メモリ使用率',
-  'dashboard.diskutilization': 'ストレージ使用率',
   'dashboard.vramutilization': '平均VRAM使用率',
   'dashboard.gpuutilization': '平均GPU使用率',
   'dashboard.usage': '使用状況',
-  'dashboard.apirequest': 'APIリクエスト',
   'dashboard.tokens': 'トークン使用量',
   'dashboard.topusers': 'トップユーザー',
-  'dashboard.activeModels': 'アクティブなモデル',
-  'dashboard.activeUsers': 'アクティブユーザー',
+  'dashboard.activeDeployments': 'Active Deployments',
   'dashboard.tokenUsageByModel': 'モデル別トークン使用量',
   'dashboard.apiRequestsByModel': 'モデル別APIリクエスト',
   'dashboard.topTokenUsageByUser': 'ユーザー別トークン使用量トップ10',
   'dashboard.topTokenUsageByApiKey': 'APIキー別トークン使用量トップ10',
-  'dashboard.runninginstances': '稼働中のインスタンス',
-  'dashboard.activeModels.name': 'モデル名',
   'dashboard.allocatevram': '割り当て済みVRAM / メモリ',
   'dashboard.usage.selectuser': 'Select users',
   'dashboard.usage.selectmodel': 'Select models',