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/en-US/dashboard.ts

@@ -1,32 +1,23 @@
 export default {
-  'dashboard.title': 'Dashboard',
   'dashboard.workers': 'Workers',
-  'dashboard.models': 'Models',
+  'dashboard.deployments': 'Deployments',
   'dashboard.clusters': 'Clusters',
   'dashboard.totalgpus': 'GPUs',
-  'dashboard.allocategpus': 'Allocated GPUs',
-  'dashboard.instances': 'Instances',
   'dashboard.systemload': 'System Load',
   'dashboard.memory': 'RAM',
-  'dashboard.disk': 'Storage',
   'dashboard.vram': 'VRAM',
   'dashboard.cpuutilization': 'Average CPU Utilization',
   'dashboard.memoryutilization': 'Average RAM Utilization',
-  'dashboard.diskutilization': 'Storage Utilization',
   'dashboard.vramutilization': 'Average VRAM Utilization',
   'dashboard.gpuutilization': 'Average GPU Utilization',
   'dashboard.usage': 'Usage',
-  'dashboard.apirequest': 'API Requests',
   'dashboard.tokens': 'Token Usage',
   'dashboard.topusers': 'Top Users',
-  'dashboard.activeModels': 'Active Models',
-  'dashboard.activeUsers': 'Active Users',
+  'dashboard.activeDeployments': 'Active Deployments',
   'dashboard.tokenUsageByModel': 'Token Usage by Model',
   'dashboard.apiRequestsByModel': 'API Requests by Model',
   'dashboard.topTokenUsageByUser': 'Top 10 Token Usage by User',
   'dashboard.topTokenUsageByApiKey': 'Top 10 Token Usage by API Key',
-  'dashboard.runninginstances': 'Running Instances',
-  'dashboard.activeModels.name': 'Model Name',
   'dashboard.allocatevram': 'Allocated VRAM / RAM',
   'dashboard.usage.selectuser': 'Select users',
   'dashboard.usage.selectmodel': 'Select models',