feat(extension): 浏览器插件 P1 MVP

新建 BillNote_extension/ 工作空间（基于 vitesse-webext 骨架，Vue 3 + Vite + UnoCSS + MV3）。

P1 MVP 范围：
- popup：自动读当前 tab URL，识别 Bilibili / YouTube / 抖音 / 快手；提交 /generate_note 后轮询 /task_status；展示 markdown，复制 + 下载 .md
- options：后端地址输入与连通性测试；从 /get_all_providers + /get_models_by_provider 拉供应商/模型列表；默认画质、截图/跳转、笔记风格
- chrome.storage.local 持久化设置与最近 30 个任务，popup 重开恢复进行中任务
- markdown 里的 /static/screenshots 路径在渲染前重写为绝对地址

后端：CORS 改用 regex，新增允许 chrome-extension:// 与 moz-extension:// 源（同时保留 localhost / 127.0.0.1 / tauri.localhost）。无新增 backend endpoint。

P2-P4（content script 悬浮按钮、cookie 直通、side panel、思维导图、RAG 问答）保留 stub 文件，不在本次范围。

去掉 vitesse-webext 自带的 simple-git-hooks postinstall 配置——它会在仓库根装 pre-commit 钩子去跑 pnpm lint-staged，但仓库根没有 package.json，会破坏所有提交流。

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

BillNote_extension/src/components/Logo.vue

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+<template>
+  <a class="icon-btn mx-2 text-2xl" rel="noreferrer" href="https://github.com/antfu/vitesse-webext" target="_blank" title="GitHub">
+    <pixelarticons-power />
+  </a>
+</template>

BillNote_extension/src/components/MarkdownView.vue

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+<script setup lang="ts">
+import { computed } from 'vue'
+import MarkdownIt from 'markdown-it'
+import { absolutizeMarkdownImages } from '~/logic/api'
+
+const props = defineProps<{ markdown: string, title?: string }>()
+
+const md = new MarkdownIt({ html: false, linkify: true, breaks: true })
+
+const html = computed(() => md.render(absolutizeMarkdownImages(props.markdown || '')))
+
+async function copy() {
+  await navigator.clipboard.writeText(props.markdown)
+}
+
+function download() {
+  const blob = new Blob([props.markdown], { type: 'text/markdown;charset=utf-8' })
+  const url = URL.createObjectURL(blob)
+  const a = document.createElement('a')
+  a.href = url
+  a.download = `${props.title || 'bilinote'}.md`
+  a.click()
+  URL.revokeObjectURL(url)
+}
+</script>
+
+<template>
+  <div class="flex flex-col gap-2">
+    <div class="flex gap-2 justify-end">
+      <button class="btn-secondary" @click="copy">复制 Markdown</button>
+      <button class="btn-secondary" @click="download">下载 .md</button>
+    </div>
+    <div class="prose prose-sm max-w-none border rounded p-3 bg-gray-50 max-h-[400px] overflow-auto" v-html="html" />
+  </div>
+</template>
+
+<style>
+.prose img { max-width: 100%; }
+.prose h1, .prose h2, .prose h3 { font-weight: 600; margin-top: 0.8em; margin-bottom: 0.4em; }
+.prose p { margin-bottom: 0.5em; line-height: 1.55; }
+.prose ul, .prose ol { padding-left: 1.4em; margin-bottom: 0.5em; }
+.prose code { background: #eee; padding: 0 4px; border-radius: 3px; font-size: 0.9em; }
+.prose a { color: #2563eb; text-decoration: underline; }
+</style>

BillNote_extension/src/components/PlatformBadge.vue

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+<script setup lang="ts">
+import { computed } from 'vue'
+import type { Platform } from '~/logic/types'
+import { PLATFORM_LABELS } from '~/logic/platform'
+
+const props = defineProps<{ platform: Platform | null }>()
+
+const colorMap: Record<Platform, string> = {
+  bilibili: 'bg-pink-100 text-pink-700',
+  youtube: 'bg-red-100 text-red-700',
+  douyin: 'bg-zinc-200 text-zinc-800',
+  kuaishou: 'bg-orange-100 text-orange-700',
+  local: 'bg-gray-100 text-gray-600',
+}
+
+const cls = computed(() => (props.platform ? colorMap[props.platform] : 'bg-gray-100 text-gray-500'))
+const label = computed(() => (props.platform ? PLATFORM_LABELS[props.platform] : '未识别'))
+</script>
+
+<template>
+  <span class="inline-flex items-center px-2 py-0.5 rounded text-xs font-medium" :class="cls">
+    {{ label }}
+  </span>
+</template>

BillNote_extension/src/components/README.md

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+## Components
+
+Components in this dir will be auto-registered and on-demand, powered by [unplugin-vue-components](https://github.com/unplugin/unplugin-vue-components).
+
+Components can be shared in all views.
+
+### Icons
+
+You can use icons from almost any icon sets by the power of [Iconify](https://iconify.design/).
+
+It will only bundle the icons you use. Check out [unplugin-icons](https://github.com/unplugin/unplugin-icons) for more details.

BillNote_extension/src/components/SharedSubtitle.vue

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+<template>
+  <p class="mt-2 opacity-50">
+    This is the {{ $app.context }} page
+  </p>
+</template>

BillNote_extension/src/components/TaskProgress.vue

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+<script setup lang="ts">
+import { computed } from 'vue'
+import type { TaskStatus } from '~/logic/types'
+
+const props = defineProps<{ status: TaskStatus, message?: string }>()
+
+const STAGE_ORDER: TaskStatus[] = ['PENDING', 'PARSING', 'DOWNLOADING', 'TRANSCRIBING', 'SUMMARIZING', 'FORMATTING', 'SAVING', 'SUCCESS']
+const STAGE_LABELS: Record<TaskStatus, string> = {
+  PENDING: '排队中',
+  PARSING: '解析中',
+  DOWNLOADING: '下载中',
+  TRANSCRIBING: '转写中',
+  SUMMARIZING: '总结中',
+  FORMATTING: '格式化',
+  SAVING: '保存中',
+  SUCCESS: '完成',
+  FAILED: '失败',
+}
+
+const currentIdx = computed(() => STAGE_ORDER.indexOf(props.status))
+const isFailed = computed(() => props.status === 'FAILED')
+</script>
+
+<template>
+  <div class="flex flex-col gap-2">
+    <div class="flex items-center gap-2 text-sm">
+      <span :class="isFailed ? 'text-red-600' : 'text-blue-600'" class="font-medium">
+        {{ STAGE_LABELS[status] }}
+      </span>
+      <span v-if="message" class="text-gray-500 text-xs truncate">{{ message }}</span>
+    </div>
+    <div v-if="!isFailed" class="flex gap-1">
+      <div
+        v-for="(s, i) in STAGE_ORDER"
+        :key="s"
+        class="h-1 flex-1 rounded-full"
+        :class="i <= currentIdx ? 'bg-blue-500' : 'bg-gray-200'"
+      />
+    </div>
+    <div v-else class="h-1 rounded-full bg-red-500" />
+  </div>
+</template>

BillNote_extension/src/components/__tests__/Logo.test.ts

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+import { describe, expect, it } from 'vitest'
+import { mount } from '@vue/test-utils'
+import Logo from '../Logo.vue'
+
+describe('logo component', () => {
+  it('should render', () => {
+    const wrapper = mount(Logo)
+
+    expect(wrapper.html()).toBeTruthy()
+  })
+})