优化: 响应式布局走查修复(断点统一+窄屏适配)

- 统一断点: Dashboard/Ideas/Projects/ProjectDetail 的响应式断点
  从 900px 改为 768px,与 AppLayout/AppSidebar 对齐(消除中间区间挤压)
- filter-bar 全局加 flex-wrap:wrap(窄屏自动换行,Ideas/Tasks/AuditLog 受益)
- IdeaDetail debate-container 窄屏双栏堆叠(@media 760px 切单列)
- modal-box min-width 改用 min(360px,90vw)(超小窗口不撑破)
- Tasks search-input 改 flex 布局(窄屏自适应宽度)

src/views/Dashboard.vue

@@ -140,8 +140,8 @@ onMounted(() => {
 
 /* ═══ Responsive ═══ */
 
-/* 窄窗口：单栏 */
-@media (max-width: 900px) {
+/* 窄窗口：单栏(与 AppLayout 768px 断点对齐) */
+@media (max-width: 768px) {
   .dashboard { padding: 12px 14px 16px; }
   .dash-grid { grid-template-columns: 1fr; }
   .dash-right { flex-direction: row; flex-wrap: wrap; gap: 10px; }

src/views/Ideas.vue

@@ -498,14 +498,11 @@ watch(() => route.params.id, (id) => {
 /* empty-state / empty-icon 已提取到 global.css 全局 */
 
 /* ===== 响应式 ===== */
-@media (max-width: 900px) {
+@media (max-width: 768px) {
   .ideas { padding: 16px; }
   .ideas-layout {
     grid-template-columns: 1fr;
   }
-  .filter-bar {
-    flex-wrap: wrap;
-  }
   .search-box {
     max-width: 100%;
     order: -1;

src/views/ProjectDetail.vue

@@ -821,7 +821,7 @@ onUnmounted(() => {
 }
 
 /* ===== 响应式 ===== */
-@media (max-width: 900px) {
+@media (max-width: 768px) {
   .project-detail { padding: 16px; }
   .detail-grid {
     grid-template-columns: 1fr;

src/views/Projects.vue

@@ -496,7 +496,7 @@ async function runImport() {
 .trash-actions { display: flex; gap: 8px; }
 
 /* ===== 响应式 ===== */
-@media (max-width: 900px) {
+@media (max-width: 768px) {
   .projects { padding: 16px; }
   .project-grid {
     grid-template-columns: 1fr;

src/views/Tasks.vue

@@ -458,6 +458,8 @@ onUnmounted(() => {
 /* 搜索框 */
 .search-input {
   width: 220px;
+  max-width: 100%;
+  flex: 1 1 220px;
   padding: 6px 12px;
   border: 0.5px solid var(--df-border);
   border-radius: var(--df-radius-sm);