feat: add i18n, platform channels page, and WeChat QR login

- Add vue-i18n with auto-detect browser language and manual toggle (EN/中文)
- Move platform channels to separate page with credential management
- Support Telegram, Discord, Slack, WhatsApp, Matrix, Feishu, Weixin, WeCom
- Add WeChat QR code login (opens in browser, polls status, auto-saves)
- Write platform credentials to ~/.hermes/.env matching hermes gateway setup
- Auto restart gateway after platform config changes
- Add settings store with per-section save for all config categories
- Persist session group collapse state across navigation
- Fix pre-existing TypeScript build errors

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/components/layout/LanguageSwitch.vue

@@ -0,0 +1,30 @@
+<script setup lang="ts">
+import { computed } from 'vue'
+import { useI18n } from 'vue-i18n'
+import { NSelect } from 'naive-ui'
+
+const { locale, availableLocales } = useI18n()
+
+const options = computed(() =>
+  availableLocales.map(loc => ({
+    label: loc === 'zh' ? '中文' : 'English',
+    value: loc,
+  })),
+)
+
+function handleChange(val: string) {
+  locale.value = val
+  localStorage.setItem('hermes_locale', val)
+}
+</script>
+
+<template>
+  <NSelect
+    :value="locale"
+    :options="options"
+    size="tiny"
+    :consistent-menu-width="false"
+    style="width: 90px"
+    @update:value="handleChange"
+  />
+</template>