feat(ui): enhance theme toggle styling and add Chinese localization

- Redesign theme toggle with improved visual effects including gradient overlays, enhanced shadows, and smoother cubic-bezier transitions
- Update toggle dimensions and icon positioning for better visual balance
- Add SVG filter effects for sun/moon icons in dark mode
- Replace English UI text with Chinese localization in MilkdownEditor
- Refactor copilotPlugin by removing unused decoration functions and improving ghost mark text node handling

src/plugins/copilotPlugin.ts

@@ -3,7 +3,6 @@ import { $prose, $ctx, $markSchema } from '@milkdown/kit/utils'
 import { parserCtx, serializerCtx } from '@milkdown/kit/core'
 import { Node as ProseNode, DOMParser, DOMSerializer } from '@milkdown/prose/model'
 import type { Ctx } from '@milkdown/kit/core'
-import { Decoration, DecorationSet } from '@milkdown/prose/view'
 import type { EditorView } from '@milkdown/prose/view'
 import { getOcrCache, OCR_SIZE_LIMIT, extractTextFromOCR } from '../utils/ocrCache'
 
@@ -119,26 +118,6 @@ function clearGhostText(view: EditorView): boolean {
   return true
 }
 
-function buildGhostBlockDecorations(state: any): DecorationSet | null {
-  const pluginState = COPILOT_PLUGIN_KEY.getState(state) as CopilotState | undefined
-  if (!pluginState || !pluginState.suggestion || pluginState.from >= pluginState.to) {
-    return null
-  }
-
-  const from = Math.max(0, Math.min(pluginState.from, state.doc.content.size))
-  const to = Math.max(from, Math.min(pluginState.to, state.doc.content.size))
-  const decorations: Decoration[] = []
-
-  state.doc.nodesBetween(from, to, (node: any, pos: number) => {
-    if (!node.isBlock || node.nodeSize <= 0) return true
-    decorations.push(Decoration.node(pos, pos + node.nodeSize, { class: 'copilot-ghost-block' }))
-    return true
-  })
-
-  if (decorations.length === 0) return null
-  return DecorationSet.create(state.doc, decorations)
-}
-
 function getCursorBeforeGhostInsert(tr: any, from: number): number {
   const mapped = tr.mapping.map(from, -1)
   return Math.max(0, Math.min(mapped, tr.doc.content.size))
@@ -167,9 +146,13 @@ function addGhostMarksToTextNodes(tr: any, from: number, to: number, markType: a
   tr.doc.nodesBetween(from, to, (node: any, pos: number) => {
     if (!node.isText || node.nodeSize <= 0) return true
 
-    const $pos = tr.doc.resolve(pos)
+    const start = Math.max(pos, from)
+    const end = Math.min(pos + node.nodeSize, to)
+    if (end <= start) return true
+
+    const $pos = tr.doc.resolve(start)
     if ($pos.parent.type.allowsMarkType?.(markType)) {
-      tr.addMark(pos, pos + node.nodeSize, markType.create())
+      tr.addMark(start, end, markType.create())
     }
     return true
   })
@@ -454,7 +437,6 @@ export const copilotPlugin = $prose((ctx) => new Plugin<CopilotState>({
     }
   },
   props: {
-    decorations: (state) => buildGhostBlockDecorations(state),
     handleKeyDown: (view, event) => {
       const hasGhost = hasGhostText(view)