✨ feat(vscode): 工单详情头部按钮改用自绘悬停提示

那排图标按钮只靠原生 title 提示：延迟长、样式是系统的，暗色主题下很突兀，
「在 Gitea 打开」更是完全没有说明。

新增 Tooltip 组件（portal 到 body，优先弹在上方，空间不够翻到下方，左右钳在
视口内，300ms 延迟），工单详情头部的打开/接管/移交/待接管/打回待办/关闭/删除
全部改用它，文案顺带写清楚每个动作的实际后果。

Claude-Session: https://claude.ai/code/session_01REdhpbaNyqWASF2HWsnTFv

vscode/webview-ui/src/components/IssueDetailPanel.tsx

@@ -8,6 +8,7 @@ import { isIssueMine, issueOwnerLogin } from '../lib/issueOwnership'
 import { toReadOnlySchema } from '../lib/readOnlySchema'
 import { COLUMN_LABELS, COLUMN_ORDER } from '../types'
 import { PropertyGrid } from './property-grid'
+import { Tooltip } from './ui/tooltip'
 
 /** 跨机绝对路径只比 basename（同名 .json）映射到本机 profiles 列表。 */
 function matchProfileOption(
@@ -616,77 +617,86 @@ export function IssueDetailPanel({
               </span>
             )
           : null}
-        <button
-          type="button"
-          onClick={() => onOpenInBrowser(issue.htmlUrl)}
-          className="inline-flex shrink-0 items-center gap-1 rounded border border-[var(--vscode-panel-border)] px-2 py-1 text-xs hover:bg-black/10 dark:hover:bg-white/10"
-        >
-          <ExternalLink className="size-3.5" />
-          {issue.source === 'youtrack' ? '在 YouTrack 打开' : '在 Gitea 打开'}
-        </button>
+        <Tooltip label={issue.source === 'youtrack' ? '在浏览器里打开这张 YouTrack 卡' : '在浏览器里打开这个 Gitea 工单'}>
+          <button
+            type="button"
+            onClick={() => onOpenInBrowser(issue.htmlUrl)}
+            className="inline-flex shrink-0 items-center gap-1 rounded border border-[var(--vscode-panel-border)] px-2 py-1 text-xs hover:bg-black/10 dark:hover:bg-white/10"
+          >
+            <ExternalLink className="size-3.5" />
+            {issue.source === 'youtrack' ? '在 YouTrack 打开' : '在 Gitea 打开'}
+          </button>
+        </Tooltip>
         {/* Close/delete write to gitea by number — hide for youtrack cards to
             avoid acting on a gitea issue of the same number. */}
         {issue.source !== 'youtrack' && !readOnly && (
           <>
             {issue.handoffAttachmentId && me !== undefined && (issue.assignees ?? []).includes(me) && (
-              <button
-                type="button"
-                disabled={isHandoffRunning(issue.number)}
-                onClick={() => onAcceptHandoff(issue.number)}
-                title={`接管（${issue.handoffFrom ?? '?'} 移交）`}
-                aria-label="接管"
-                className="inline-flex shrink-0 items-center gap-1 rounded border border-green-500/60 bg-green-500/10 px-2 py-1 text-xs text-green-500 hover:bg-green-500/20 disabled:opacity-50"
-              >
-                {isHandoffRunning(issue.number) ? <Loader2 className="size-3.5 animate-spin" /> : <Download className="size-3.5" />}
-                接管
-              </button>
+              <Tooltip label={`接管 ${issue.handoffFrom ?? '?'} 移交过来的工单：拉回会话记录和 worktree`}>
+                <button
+                  type="button"
+                  disabled={isHandoffRunning(issue.number)}
+                  onClick={() => onAcceptHandoff(issue.number)}
+                  aria-label="接管"
+                  className="inline-flex shrink-0 items-center gap-1 rounded border border-green-500/60 bg-green-500/10 px-2 py-1 text-xs text-green-500 hover:bg-green-500/20 disabled:opacity-50"
+                >
+                  {isHandoffRunning(issue.number) ? <Loader2 className="size-3.5 animate-spin" /> : <Download className="size-3.5" />}
+                  接管
+                </button>
+              </Tooltip>
             )}
             {!issue.handoffAttachmentId && issue.column !== 'done' && ((issue.assignees ?? []).length === 0 || (me !== undefined && (issue.assignees ?? []).includes(me))) && (
-              <button
-                type="button"
-                disabled={isHandoffRunning(issue.number)}
-                onClick={() => onStartHandoff(issue.number)}
-                title="移交给同事"
-                aria-label="移交"
-                className="inline-flex shrink-0 items-center justify-center rounded border border-[var(--vscode-panel-border)] p-1 text-xs text-[var(--vscode-foreground)] hover:border-blue-500/60 hover:bg-blue-500/10 hover:text-blue-500 disabled:opacity-50"
-              >
-                {isHandoffRunning(issue.number) ? <Loader2 className="size-3.5 animate-spin" /> : <ArrowRightLeft className="size-3.5" />}
-              </button>
+              <Tooltip label="移交给同事：把会话记录打包传过去，对方接管后继续做">
+                <button
+                  type="button"
+                  disabled={isHandoffRunning(issue.number)}
+                  onClick={() => onStartHandoff(issue.number)}
+                  aria-label="移交"
+                  className="inline-flex shrink-0 items-center justify-center rounded border border-[var(--vscode-panel-border)] p-1 text-xs text-[var(--vscode-foreground)] hover:border-blue-500/60 hover:bg-blue-500/10 hover:text-blue-500 disabled:opacity-50"
+                >
+                  {isHandoffRunning(issue.number) ? <Loader2 className="size-3.5 animate-spin" /> : <ArrowRightLeft className="size-3.5" />}
+                </button>
+              </Tooltip>
             )}
             {issue.handoffAttachmentId && !(me !== undefined && (issue.assignees ?? []).includes(me)) && (
-              <span className="inline-flex shrink-0 items-center rounded border border-[var(--vscode-panel-border)] px-1.5 py-0.5 text-[10px] opacity-70" title={`${issue.handoffFrom ?? '?'} 已移交，等待 ${(issue.assignees ?? []).join(', ') || '?'} 接管`}>
-                待接管
-              </span>
+              <Tooltip label={`${issue.handoffFrom ?? '?'} 已移交，等待 ${(issue.assignees ?? []).join(', ') || '?'} 接管`}>
+                <span className="inline-flex shrink-0 items-center rounded border border-[var(--vscode-panel-border)] px-1.5 py-0.5 text-[10px] opacity-70">
+                  待接管
+                </span>
+              </Tooltip>
             )}
             {(issue.column === 'in-progress' || issue.column === 'review') && (
+              <Tooltip label="打回待办：卡片挪回待办列，会话和 worktree 不动">
+                <button
+                  type="button"
+                  onClick={() => onResetToTodo(issue.number)}
+                  aria-label="重置为待办"
+                  className="inline-flex shrink-0 items-center justify-center rounded border border-[var(--vscode-panel-border)] p-1 text-xs text-[var(--vscode-foreground)] hover:border-yellow-500/60 hover:bg-yellow-500/10 hover:text-yellow-500"
+                >
+                  <RotateCcw className="size-3.5" />
+                </button>
+              </Tooltip>
+            )}
+            <Tooltip label="关闭工单：Gitea 上置为 closed，卡片从看板消失，可在 Gitea 里重开">
               <button
                 type="button"
-                onClick={() => onResetToTodo(issue.number)}
-                title="重置为待办"
-                aria-label="重置为待办"
+                onClick={() => onCloseIssue(issue.number)}
+                aria-label="关闭工单"
                 className="inline-flex shrink-0 items-center justify-center rounded border border-[var(--vscode-panel-border)] p-1 text-xs text-[var(--vscode-foreground)] hover:border-yellow-500/60 hover:bg-yellow-500/10 hover:text-yellow-500"
               >
-                <RotateCcw className="size-3.5" />
+                <CircleSlash className="size-3.5" />
               </button>
-            )}
-            <button
-              type="button"
-              onClick={() => onCloseIssue(issue.number)}
-              title="关闭工单"
-              aria-label="关闭工单"
-              className="inline-flex shrink-0 items-center justify-center rounded border border-[var(--vscode-panel-border)] p-1 text-xs text-[var(--vscode-foreground)] hover:border-yellow-500/60 hover:bg-yellow-500/10 hover:text-yellow-500"
-            >
-              <CircleSlash className="size-3.5" />
-            </button>
-            <button
-              type="button"
-              onClick={() => issue && onDeleteIssue?.(issue.number)}
-              title="删除工单（不可撤销）"
-              aria-label="删除工单"
-              className="inline-flex shrink-0 items-center justify-center rounded border border-[var(--vscode-panel-border)] p-1 text-xs text-[var(--vscode-foreground)] hover:border-red-500/60 hover:bg-red-500/10 hover:text-red-500"
-            >
-              <Trash2 className="size-3.5" />
-            </button>
+            </Tooltip>
+            <Tooltip label="删除工单：从 Gitea 彻底删掉，不可撤销">
+              <button
+                type="button"
+                onClick={() => issue && onDeleteIssue?.(issue.number)}
+                aria-label="删除工单"
+                className="inline-flex shrink-0 items-center justify-center rounded border border-[var(--vscode-panel-border)] p-1 text-xs text-[var(--vscode-foreground)] hover:border-red-500/60 hover:bg-red-500/10 hover:text-red-500"
+              >
+                <Trash2 className="size-3.5" />
+              </button>
+            </Tooltip>
           </>
         )}
       </div>