新增: 文件浏览器收尾(滚动条/阶段进度条/空状态/骨架屏/工程下拉)

- 提交之前未提交的滚动条与布局修复
- 移除阶段进度条死代码(模板+CSS+常量)
- 文件预览空状态加图标引导
- 变更视图加载骨架屏
- 工程选择器改为自定义下拉(显示工程路径)

src/components/project/FilePreview.vue

@@ -35,7 +35,8 @@
     <div class="preview-body">
       <!-- 未选文件占位 -->
       <div v-if="!filePath" class="preview-placeholder">
-        {{ $t('fileExplorer.selectFileHint') }}
+        <div class="preview-placeholder-icon">📄</div>
+        <div class="preview-placeholder-text">{{ $t('fileExplorer.selectFileHint') }}</div>
       </div>
 
       <!-- 加载中 -->
@@ -75,9 +76,9 @@
       </div>
 
       <!-- 文本/代码(highlight.js 语法高亮 + 行号;非 diff 模式时显示) -->
-      <div v-else class="preview-code-wrap">
-        <div class="preview-line-numbers" ref="lineNumRef">
-          <div v-for="n in lineCount" :key="n" class="preview-line-num" :class="{ 'is-active': n === activeLine }">{{ n }}</div>
+      <div v-else class="preview-code-scroll">
+        <div class="preview-line-numbers" aria-hidden="true">
+          <div v-for="n in lineCount" :key="n" class="preview-line-num">{{ n }}</div>
         </div>
         <pre class="preview-code"><code :class="hljsClass" v-html="htmlContent"></code></pre>
       </div>
@@ -116,10 +117,6 @@ const lineCount = computed(() => {
   return lines.length
 })
 
-/** 当前激活行(预留:后续可点击行号跳转/选中高亮)。 */
-const activeLine = ref<number | null>(null)
-const lineNumRef = ref<HTMLElement | null>(null)
-
 /** Diff 显示控制 */
 const showDiff = ref(false)
 const diffContent = ref('')
@@ -398,6 +395,15 @@ onUnmounted(() => {
   min-height: 200px;
 }
 
+.preview-placeholder-icon {
+  font-size: 48px;
+  opacity: 0.4;
+}
+
+.preview-placeholder-text {
+  font-size: 13px;
+}
+
 .preview-error { color: #e05050; }
 .binary-icon { font-size: 32px; opacity: 0.5; }
 
@@ -423,24 +429,22 @@ onUnmounted(() => {
   font-size: 12.5px;
   line-height: 1.55;
   white-space: pre;
-  overflow: auto;
+  overflow: visible;
   tab-size: 2;
-  flex: 1;
   min-width: 0;
-  min-height: 0;
 }
 
 .preview-code code { font-family: inherit; }
 
-/* 行号 + 代码并排容器 */
-.preview-code-wrap {
+/* 行号 + 代码共享同一个滚动容器 */
+.preview-code-scroll {
   display: flex;
-  overflow: hidden;
+  flex: 1;
   min-height: 0;
-  flex: 1 1 0;
+  overflow: auto;
 }
 
-/* 行号列 */
+/* 行号列 — sticky 固定在左侧,跟随滚动容器一起滚 */
 .preview-line-numbers {
   flex-shrink: 0;
   padding: 14px 0;
@@ -449,13 +453,16 @@ onUnmounted(() => {
   background: rgba(255, 255, 255, 0.03);
   border-right: 0.5px solid var(--df-border);
   user-select: none;
-  overflow: hidden;
+  position: sticky;
+  left: 0;
+  z-index: 1;
+  align-self: flex-start;
 }
 
 .preview-line-num {
   padding: 0 10px 0 8px;
   font-family: var(--df-font-mono, 'Cascadia Code', Consolas, monospace);
-  font-size: 12px;
+  font-size: 12.5px;
   line-height: 1.55;
   color: var(--df-text-dim);
   opacity: 0.5;