fix(admin): align wrapped usage filters

[LvyuanW]

Summary

• switch admin usage filters from a wrapping flex row to a responsive grid so wrapped rows stay visually aligned
• keep the action buttons separate from the filter grid so the main page and cleanup dialog both retain stable layouts
• scope the change to the shared usage filters component only

Testing

• pnpm exec vue-tsc --noEmit
• pnpm exec vitest run src/components/admin/usage/tests/UsageTable.spec.ts