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/kanban-task-card.test.ts

@@ -2,6 +2,7 @@
 import { afterEach, describe, expect, it, vi } from 'vitest'
 import { defineComponent } from 'vue'
 import { mount } from '@vue/test-utils'
+import ArcoVue from '@arco-design/web-vue'
 
 vi.mock('vue-i18n', () => ({
   useI18n: () => ({
@@ -19,12 +20,16 @@ vi.mock('vue-i18n', () => ({
   }),
 }))
 
-vi.mock('naive-ui', () => ({
-  NTooltip: defineComponent({
-    name: 'NTooltip',
-    template: '<div class="n-tooltip-stub"><slot name="trigger" /><div class="tooltip-content"><slot /></div></div>',
-  }),
-}))
+/**
+ * Arco's a-tooltip only renders its content in a teleported popup, so it is
+ * stubbed under Arco's *internal* component name — stubs key off that, not the
+ * `a-*` template tag, because Arco is registered globally via `app.use(ArcoVue)`.
+ */
+const ATooltipStub = defineComponent({
+  name: 'Tooltip',
+  props: ['content'],
+  template: '<div class="arco-tooltip-stub"><div class="tooltip-content">{{ content }}</div><slot /></div>',
+})
 
 vi.mock('@/components/hermes/profiles/ProfileAvatar.vue', () => ({
   default: defineComponent({
@@ -46,6 +51,12 @@ describe('KanbanTaskCard i18n', () => {
     vi.setSystemTime(new Date('2026-05-08T03:00:00Z'))
 
     const wrapper = mount(KanbanTaskCard, {
+      global: {
+        plugins: [ArcoVue],
+        stubs: {
+          Tooltip: ATooltipStub,
+        },
+      },
       props: {
         assigneeAvatar: { type: 'generated', seed: 'alice-seed' },
         task: {