Add image listing and asset management

Show images in asset directories with preview, rename, replacement, and trash recovery. Update local Markdown references when images move and restore original files if related metadata cannot be committed.

Refresh image previews after replacement and compare actual contents when deduplicating subsequent uploads.

web/src/editor/livepreview.ts

@@ -1,5 +1,5 @@
 import { syntaxTree } from '@codemirror/language'
-import { Facet, type EditorState, type Range } from '@codemirror/state'
+import { StateEffect, Facet, type EditorState, type Range } from '@codemirror/state'
 import { Decoration, EditorView, ViewPlugin, type DecorationSet, type ViewUpdate } from '@codemirror/view'
 import type { SyntaxNode } from '@lezer/common'
 import { codeContentRange, fenceLanguage, fencedCodeAt } from './codeblocks'
@@ -21,6 +21,9 @@ export const resolveImageUrl = Facet.define<(src: string) => string, (src: strin
   combine: (values) => values[0] ?? ((src) => src),
 })
 
+// 图片文件原位替换时重建预览，不改变正文、选区或撤销历史。
+export const refreshImages = StateEffect.define<null>()
+
 const hidden = Decoration.replace({})
 const inlineCode = Decoration.mark({ class: 'cm-rm-inline-code' })
 const linkText = Decoration.mark({ class: 'cm-rm-link' })
@@ -328,6 +331,7 @@ const livePreviewPlugin = ViewPlugin.fromClass(
       }
       if (
         this.stale ||
+        u.transactions.some((tr) => tr.effects.some((effect) => effect.is(refreshImages))) ||
         u.docChanged ||
         u.viewportChanged ||
         u.selectionSet ||