feat(editor): add Markdown rendering for ghost text and optimize prompt system

- Implement Markdown parsing for ghost text using Milkdown parser
- Add support for both block and inline content in ghost text
- Refactor prompt system with comprehensive rules and examples
- Adjust LLM parameters: increase temperature to 0.7, add repeat_penalty
- Add CSS styles for formatted ghost text (bold, italic, code, links)
- Add documentation for Copilot prompt system and ghost text rendering

src/components/MilkdownEditor.vue

@@ -315,10 +315,27 @@ onUnmounted(() => {
     color: #999;
     opacity: 0.6;
     pointer-events: none;
-    white-space: pre-wrap;
 }
 
 .copilot-ghost-text.copilot-loading {
     opacity: 0.4;
 }
+
+.copilot-ghost-text strong,
+.copilot-ghost-text em,
+.copilot-ghost-text code,
+.copilot-ghost-text a {
+    color: inherit;
+    opacity: inherit;
+}
+
+.copilot-ghost-text code {
+    background-color: rgba(0, 0, 0, 0.05);
+    padding: 0.2em 0.4em;
+    border-radius: 3px;
+}
+
+.copilot-ghost-text a {
+    text-decoration: underline;
+}
 </style>