Phase 007: migrate every remaining view from naive-ui to Arco Design Vue

The project now has exactly one UI library. Every naive-ui component in
packages/client/src is replaced by its Arco equivalent across 24 views and
roughly 80 components, and naive-ui is dropped from package.json along with
its transitive vueuc / @css-render / vdirs / seemly dependencies.

The migration is rendering-layer only. No store logic, no API contract, and
no /chat-run payload was touched.

Three classes of leftover were invisible to `grep naive-ui` and are now
covered by tests/client/no-naive-ui.test.ts, which asserts all three:
  - dead .n-* class names in style blocks
  - dead --n-* custom properties
  - naive-ui in package.json

Notable behavioural traps handled along the way, recorded in
docs/arco-migration-rules.md:
  - a-input-password defaults to masked; passing default-visibility="false"
    would have exposed API keys in clear text
  - a-upload fires a real XHR unless auto-upload is false
  - nested Trigger components fight over the first element child, so the
    group-chat settings dropdown was flattened
  - Arco renders tooltip default-slot text inline, which was silently
    collapsing the chat and group-chat toolbars

tests/client/usage-view-period.test.ts

@@ -2,6 +2,7 @@
 import { beforeEach, describe, expect, it, vi } from 'vitest'
 import { defineComponent } from 'vue'
 import { flushPromises, mount } from '@vue/test-utils'
+import ArcoVue from '@arco-design/web-vue'
 
 const mockUsageStore = vi.hoisted(() => ({
   isLoading: false,
@@ -29,22 +30,6 @@ vi.mock('vue-i18n', () => ({
   }),
 }))
 
-vi.mock('naive-ui', () => ({
-  NButton: defineComponent({
-    name: 'NButton',
-    props: {
-      loading: Boolean,
-      type: String,
-      secondary: Boolean,
-      quaternary: Boolean,
-      size: String,
-      ariaPressed: [Boolean, String],
-    },
-    emits: ['click'],
-    template: '<button class="n-button-stub" :data-type="type" :aria-pressed="ariaPressed" @click="$emit(\'click\')"><slot /></button>',
-  }),
-}))
-
 vi.mock('@/components/hermes/usage/StatCards.vue', () => ({
   default: defineComponent({ name: 'StatCards', template: '<section class="stat-cards-stub" />' }),
 }))
@@ -74,14 +59,14 @@ describe('UsageView period selector', () => {
   })
 
   it('loads the default 30-day period on mount', async () => {
-    mount(UsageView)
+    mount(UsageView, { global: { plugins: [ArcoVue] } })
     await flushPromises()
 
     expect(mockUsageStore.loadSessions).toHaveBeenCalledWith(30)
   })
 
   it('lets users switch usage statistics between common dashboard periods', async () => {
-    const wrapper = mount(UsageView)
+    const wrapper = mount(UsageView, { global: { plugins: [ArcoVue] } })
 
     const periodButtons = wrapper.findAll('.period-option')
     expect(periodButtons.map(button => button.text())).toEqual(['7d', '30d', '90d', '365d'])
@@ -89,8 +74,11 @@ describe('UsageView period selector', () => {
 
     await periodButtons[0].trigger('click')
     expect(mockUsageStore.loadSessions).toHaveBeenLastCalledWith(7)
-    expect(periodButtons[0].attributes('data-type')).toBe('primary')
+    // Arco expresses the button variant through classes, not a data-type attribute.
+    expect(periodButtons[0].classes()).toContain('arco-btn-secondary')
+    expect(periodButtons[1].classes()).toContain('arco-btn-text')
     expect(periodButtons[0].attributes('aria-pressed')).toBe('true')
+    expect(periodButtons[1].attributes('aria-pressed')).toBe('false')
 
     await wrapper.find('.refresh-button').trigger('click')
     expect(mockUsageStore.loadSessions).toHaveBeenLastCalledWith(7)