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/FileExplorer.vue

@@ -9,14 +9,24 @@
     <div class="explorer-toolbar">
       <div class="toolbar-left">
         <!-- 多工程下拉(单工程隐藏) -->
-        <select
-          v-if="modules.length > 1"
-          class="module-select"
-          :value="currentModuleId"
-          @change="onModuleChange"
-        >
-          <option v-for="m in modules" :key="m.id" :value="m.id">{{ m.name }}</option>
-        </select>
+        <div v-if="modules.length > 1" class="module-dropdown">
+          <button class="module-select" @click="moduleDropdownOpen = !moduleDropdownOpen">
+            <span class="module-select-name">{{ currentModule?.name ?? '...' }}</span>
+            <span class="module-select-arrow" :class="{ open: moduleDropdownOpen }">▾</span>
+          </button>
+          <div v-if="moduleDropdownOpen" class="module-dropdown-menu" @click.stop>
+            <div
+              v-for="m in modules"
+              :key="m.id"
+              class="module-dropdown-item"
+              :class="{ active: m.id === currentModuleId }"
+              @click="onModuleSelect(m.id)"
+            >
+              <span class="module-dropdown-name">{{ m.name }}</span>
+              <span v-if="m.path" class="module-dropdown-path" :title="m.path">{{ m.path }}</span>
+            </div>
+          </div>
+        </div>
 
         <!-- 路径面包屑 -->
         <nav class="breadcrumb">
@@ -160,6 +170,7 @@ const { t } = useI18n()
 const modules = ref<ProjectModuleRecord[]>([])
 const currentModuleId = ref<string>('')
 const refreshing = ref(false)
+const moduleDropdownOpen = ref(false)
 
 // 新增工程弹窗
 const showAddModule = ref(false)
@@ -216,10 +227,10 @@ function resetTreeState() {
   selectedFileGitStatus.value = undefined
 }
 
-/** 切换工程(下拉变更)。 */
-function onModuleChange(e: Event) {
-  const target = e.target as HTMLSelectElement
-  currentModuleId.value = target.value
+/** 自定义下拉选择工程。 */
+function onModuleSelect(id: string) {
+  currentModuleId.value = id
+  moduleDropdownOpen.value = false
   resetTreeState()
 }
 
@@ -310,6 +321,9 @@ function onChangeFileSelect(path: string) {
 
 watch(() => props.projectId, loadModules, { immediate: true })
 
+// 点击外部关闭工程下拉
+document.addEventListener('click', () => { moduleDropdownOpen.value = false })
+
 /** 提交新增工程。 */
 async function onAddModule() {
   if (addingModule.value) return
@@ -340,6 +354,7 @@ async function onAddModule() {
   display: flex;
   flex-direction: column;
   height: 100%;
+  max-height: 100%;
   background: var(--df-bg);
   border: 0.5px solid var(--df-border);
   border-radius: var(--df-radius-lg, 8px);
@@ -367,6 +382,9 @@ async function onAddModule() {
 }
 
 .module-select {
+  display: inline-flex;
+  align-items: center;
+  gap: 6px;
   padding: 5px 10px;
   background: var(--df-bg);
   border: 0.5px solid var(--df-border);
@@ -377,9 +395,54 @@ async function onAddModule() {
   max-width: 180px;
 }
 
-.module-select:focus {
-  outline: none;
-  border-color: var(--df-accent);
+.module-select:hover { border-color: var(--df-accent); }
+.module-select-name { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+.module-select-arrow {
+  font-size: 10px;
+  color: var(--df-text-dim);
+  transition: transform 0.15s;
+}
+.module-select-arrow.open { transform: rotate(180deg); }
+
+.module-dropdown { position: relative; flex-shrink: 0; }
+
+.module-dropdown-menu {
+  position: absolute;
+  top: calc(100% + 4px);
+  left: 0;
+  min-width: 220px;
+  max-width: 320px;
+  background: var(--df-bg-card);
+  border: 0.5px solid var(--df-border);
+  border-radius: var(--df-radius-sm, 4px);
+  box-shadow: 0 6px 16px rgba(0,0,0,0.25);
+  z-index: 20;
+  max-height: 280px;
+  overflow-y: auto;
+  scrollbar-width: thin;
+}
+
+.module-dropdown-item {
+  display: flex;
+  flex-direction: column;
+  gap: 2px;
+  padding: 8px 12px;
+  cursor: pointer;
+  border-bottom: 0.5px solid rgba(255,255,255,0.04);
+}
+.module-dropdown-item:last-child { border-bottom: none; }
+.module-dropdown-item:hover { background: rgba(255,255,255,0.04); }
+.module-dropdown-item.active {
+  background: rgba(255,255,255,0.06);
+  border-left: 2px solid var(--df-accent);
+}
+.module-dropdown-name { font-size: 12px; color: var(--df-text); }
+.module-dropdown-path {
+  font-size: 10px;
+  color: var(--df-text-dim);
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
 }
 
 /* 面包屑 */
@@ -458,6 +521,7 @@ async function onAddModule() {
   flex: 1;
   display: flex;
   overflow: hidden;
+  min-height: 0;
 }
 
 /* 左侧边栏(视图切换 + 内容) */
@@ -564,8 +628,8 @@ async function onAddModule() {
 .explorer-preview {
   flex: 1;
   min-width: 0;
+  min-height: 0;
   overflow: hidden;
-  scrollbar-width: thin;
 }
 
 .preview-placeholder-inline {