feat(MilkdownEditor): add file upload support for documents and text files

Added new upload functionality to the editor supporting doc/docx/ppt/pptx/pdf/zip/txt/json files. Includes:
- New upload button with file input
- File type detection utilities (isTextFile, isConvertibleFile)
- Initial markdown sync with trailing whitespace normalization
- Warning messages for unsupported file types

src/components/MilkdownEditor.vue

@@ -32,6 +32,21 @@
     </div>
 
     <div class="action-buttons">
+      <button
+        type="button"
+        class="action-btn"
+        :aria-label="t('uploadFile')"
+        :title="t('uploadFile')"
+        @click="triggerFileUpload"
+      >
+        <svg width="20" height="20" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+          <path d="M14 2H6a2 2 0 0 0-2 2v16a2 2 0 0 0 2 2h12a2 2 0 0 0 2-2V8z"/>
+          <polyline points="14 2 14 8 20 8"/>
+        </svg>
+        <span class="btn-tooltip">{{ t('uploadFile') }}</span>
+      </button>
+      <input type="file" ref="uploadFileInputRef" @change="handleUploadFile" accept="image/*,.doc,.docx,.ppt,.pptx,.pdf,.zip,.txt,.json" style="display:none">
+
       <button
         type="button"
         class="action-btn"
@@ -133,7 +148,7 @@
 
 <script setup>
 import { onMounted, onUnmounted, ref, computed, watch } from 'vue'
-import { replaceAll } from '@milkdown/kit/utils'
+import { replaceAll, replaceRange } from '@milkdown/kit/utils'
 import { Crepe } from '@milkdown/crepe'
 import { editorViewCtx, serializerCtx } from '@milkdown/kit/core'
 import { Selection } from '@milkdown/prose/state'
@@ -143,14 +158,17 @@ import { mermaidRenderPreview, codeBlockConfig } from '../plugins/mermaidPlugin'
 import { fetchSuggestion } from '../utils/api.js'
 import { useSettingsStore } from '../stores/settings'
 import { OCR_URL } from '../utils/config.js'
+import { convertFileToMarkdown } from '../utils/convert.js'
 import { setOcrCache, clearOcrCache, clearAllOcrCache, IMAGE_SIZE_LIMIT, calculateImageHash, getOcrByHash, setOcrByHash } from '../utils/ocrCache.js'
 
 const emit = defineEmits(['update:markdown'])
 const settings = useSettingsStore()
 const t = (key) => settings.t[key]
+const initialMarkdown = computed(() => settings.initialMarkdown)
 
 const root = ref(null)
 const fileInputRef = ref(null)
+const uploadFileInputRef = ref(null)
 const imageInputRef = ref(null)
 const cameraInputRef = ref(null)
 const aiEnabled = ref(true)
@@ -182,6 +200,48 @@ const objectUrls = new Set()
 const IMAGE_NODE_TYPES = new Set(['image', 'image-block', 'imageBlock'])
 const MARKDOWN_EXT_RE = /\.md$/i
 const IMAGE_EXT_RE = /\.(png|jpe?g|gif|webp|bmp|svg|heic|heif|avif)$/i
+const CONVERT_EXT_RE = /\.(docx?|pptx?|pdf|zip)$/i
+const TEXT_EXT_RE = /\.(txt|json)$/i
+const TEXT_MIME_TYPES = new Set(['text/plain', 'application/json'])
+const CONVERT_MIME_TYPES = new Set([
+  'application/msword',
+  'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
+  'application/vnd.ms-powerpoint',
+  'application/vnd.openxmlformats-officedocument.presentationml.presentation',
+  'application/pdf',
+  'application/zip',
+  'application/x-zip-compressed',
+])
+let lastInitialMarkdown = initialMarkdown.value
+
+const normalizeTrailingWhitespace = (value) => (value || '').replace(/\s+$/, '')
+
+const syncInitialMarkdown = async (nextValue) => {
+  if (!crepe) {
+    lastInitialMarkdown = nextValue
+    return
+  }
+
+  try {
+    const current = await crepe.getMarkdown()
+    const normalizedCurrent = normalizeTrailingWhitespace(current)
+    const normalizedLast = normalizeTrailingWhitespace(lastInitialMarkdown)
+    if (!normalizedCurrent || normalizedCurrent === normalizedLast) {
+      crepe.editor.action(replaceAll(nextValue))
+    }
+  } catch {
+    // Ignore sync errors
+  } finally {
+    lastInitialMarkdown = nextValue
+  }
+}
+
+watch(
+  () => settings.initialMarkdown,
+  (nextValue) => {
+    void syncInitialMarkdown(nextValue)
+  }
+)
 
 const revokeObjectUrl = (url) => {
   if (!objectUrls.has(url)) return
@@ -312,8 +372,36 @@ const isImageFile = (file) => {
   return type.startsWith('image/') || IMAGE_EXT_RE.test(name)
 }
 
+const isTextFile = (file) => {
+  if (!file) return false
+  const name = (file.name || '').toLowerCase()
+  const type = (file.type || '').toLowerCase()
+  return TEXT_EXT_RE.test(name) || TEXT_MIME_TYPES.has(type)
+}
+
+const isConvertibleFile = (file) => {
+  if (!file) return false
+  const name = (file.name || '').toLowerCase()
+  const type = (file.type || '').toLowerCase()
+  return CONVERT_EXT_RE.test(name) || CONVERT_MIME_TYPES.has(type)
+}
+
 const warnUnsupportedUploadType = () => {
-  alert(t('uploadFileTypeWarning') || 'Only Markdown (.md) files and image files are supported.')
+  alert(t('uploadMdTypeWarning') || 'Only Markdown (.md) files and image files are supported.')
+}
+
+const warnUnsupportedInsertType = () => {
+  alert(t('uploadFileTypeWarning') || 'Unsupported file type. Supported: doc/docx/ppt/pptx/pdf/zip, images, txt/json.')
+}
+
+const warnUploadError = (message = '') => {
+  const base = t('uploadFileError') || 'File upload failed.'
+  alert(message ? `${base}\n${message}` : base)
+}
+
+const warnConvertError = (message = '') => {
+  const base = t('uploadConvertError') || 'File conversion failed.'
+  alert(message ? `${base}\n${message}` : base)
 }
 
 const warnImageTooLarge = () => {
@@ -403,7 +491,7 @@ onMounted(async () => {
     
     crepe = new Crepe({
         root: root.value,
-        defaultValue: '# Welcome to LLM-IN-TEXT\n\nA instant LLM system\n\nStart your creative work below...',
+        defaultValue: initialMarkdown.value || '',
         features: {
             [Crepe.Feature.Latex]: true,
             [Crepe.Feature.ImageBlock]: true,
@@ -591,6 +679,72 @@ const insertImageAtCursor = (src) => {
     })
 }
 
+const insertMarkdownAtCursor = (markdown) => {
+    if (!crepe || !markdown) return
+    crepe.editor.action((ctx) => {
+        const view = ctx.get(editorViewCtx)
+        const { from, to } = view.state.selection
+        replaceRange(markdown, { from, to })(ctx)
+        view.focus()
+    })
+}
+
+const buildCodeBlock = (file, text) => {
+    const name = (file?.name || '').toLowerCase()
+    const lang = name.endsWith('.json') ? 'json' : 'text'
+    return `\n\`\`\`${lang}\n${text}\n\`\`\`\n`
+}
+
+const triggerFileUpload = () => {
+    uploadFileInputRef.value?.click()
+}
+
+const handleUploadFile = async (event) => {
+    const input = event.target
+    const file = input.files?.[0]
+    if (!file) return
+
+    const convertible = isConvertibleFile(file)
+    try {
+        if (isImageFile(file)) {
+            const objectUrl = await prepareImageFile(file)
+            if (objectUrl) {
+                clearCurrentGhost()
+                insertImageAtCursor(objectUrl)
+            }
+            return
+        }
+
+        if (isTextFile(file)) {
+            const text = await file.text()
+            clearCurrentGhost()
+            insertMarkdownAtCursor(buildCodeBlock(file, text))
+            return
+        }
+
+        if (convertible) {
+            const markdown = await convertFileToMarkdown(file)
+            if (!markdown) {
+                throw new Error('No markdown returned')
+            }
+            clearCurrentGhost()
+            insertMarkdownAtCursor(markdown)
+            return
+        }
+
+        warnUnsupportedInsertType()
+    } catch (e) {
+        const message = e instanceof Error ? e.message : ''
+        if (convertible) {
+            warnConvertError(message)
+        } else {
+            warnUploadError(message)
+        }
+    } finally {
+        input.value = ''
+    }
+}
+
 const handleImageUpload = async (event) => {
     const input = event.target
     const file = input.files?.[0]