✨ feat(vscode): 会话交接改走阿里云 OSS 收件箱、换 xz 压缩，另加从 env 文件配置移交存储的 URI

- 会话包传到 OSS 上收件人的收件箱 spx-handoff/<owner>/<repo>/session/<收件人>/<sid>!<发送人>!<会话名>.tar.xz，对象私有；owner/repo/收件人转小写
- 待接收列表就是列自己的收件箱；同一会话再交给同一人先删旧包；接收后删包，包已被别处收走时提示并刷新
- 打包换成 xz 1 级，和工单移交共用 packHandoff / unpackHandoff，删掉 gzip 版
- 删掉邮箱工单整套（mailboxIssue、MAILBOX_*、isMailboxIssue 及看板 / webhook 里的过滤、附件名编解码）和不再用的 Gitea 附件、标签、建工单接口
- session-handoff/accept 与待接收项改用 OSS 对象 key 标识
- 没配移交存储时发送、接收、刷新都提示去配，刷新回空列表
- 进度提示照工单移交：同一条提示依次显示打包、上传、下载多少 MB、解包、装会话
- 新增 URI configure-handoff-store?envFile=<绝对路径>：读 OSS_ENDPOINT / OSS_BUCKET_NAME / OSS_ACCESS_KEY / OSS_SECRET_KEY 保存，和命令共用 saveHandoffStore；URI 入口按 path 统一分发，未知 path 报错

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

@@ -91,7 +91,7 @@ export interface BottomTabsProps {
   onImportNamedSession: (sessionId: string, name: string) => void
   pendingHandoffs: SessionHandoffPendingItem[]
   onSessionHandoff: (sessionId: string) => void
-  onAcceptSessionHandoff: (attachmentId: number) => void
+  onAcceptSessionHandoff: (key: string) => void
 }
 
 export function BottomTabs(props: BottomTabsProps) {

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

@@ -29,7 +29,7 @@ interface ManagedSessionsPanelProps {
   onImport: (sessionId: string, name: string) => void
   pendingHandoffs: SessionHandoffPendingItem[]
   onHandoff: (sessionId: string) => void
-  onAcceptHandoff: (attachmentId: number) => void
+  onAcceptHandoff: (key: string) => void
 }
 
 function basename(p?: string): string {
@@ -254,7 +254,7 @@ export function ManagedSessionsPanel({
           <div className="mb-1 text-[10px] text-[var(--vscode-descriptionForeground)]">待接收</div>
           <ul className="flex flex-col gap-1">
             {pendingHandoffs.map(p => (
-              <li key={p.attachmentId} className="flex items-center gap-2">
+              <li key={p.key} className="flex items-center gap-2">
                 <div className="min-w-0 flex-1">
                   <div className="truncate text-xs">{p.name || p.sid.slice(0, 8)}</div>
                   <div className="truncate text-[10px] text-[var(--vscode-descriptionForeground)]">
@@ -265,7 +265,7 @@ export function ManagedSessionsPanel({
                 </div>
                 <button
                   type="button"
-                  onClick={() => onAcceptHandoff(p.attachmentId)}
+                  onClick={() => onAcceptHandoff(p.key)}
                   className="shrink-0 rounded bg-[var(--vscode-button-background)] px-2 py-1 text-xs text-[var(--vscode-button-foreground)] hover:bg-[var(--vscode-button-hoverBackground)]"
                 >
                   接收

vscode/webview-ui/src/hooks/useManagedSessions.ts

@@ -34,7 +34,7 @@ export interface UseManagedSessionsResult {
   sessionHandoffUsers: string[] | null
   startSessionHandoff: (sessionId: string) => void
   submitSessionHandoff: (sessionId: string, to: string) => void
-  acceptSessionHandoff: (attachmentId: number) => void
+  acceptSessionHandoff: (key: string) => void
   refreshSessionHandoffs: () => void
 }
 
@@ -102,8 +102,8 @@ export function useManagedSessions(): UseManagedSessionsResult {
     postMessage({ type: 'session-handoff/start', sessionId, to })
   }, [])
 
-  const acceptSessionHandoff = useCallback((attachmentId: number): void => {
-    postMessage({ type: 'session-handoff/accept', attachmentId })
+  const acceptSessionHandoff = useCallback((key: string): void => {
+    postMessage({ type: 'session-handoff/accept', key })
   }, [])
 
   const refreshSessionHandoffs = useCallback((): void => {

vscode/webview-ui/src/lib/messages.ts

@@ -52,11 +52,11 @@ export interface IssueChatComment {
   systemText?: string
 }
 
+/** 我收件箱里一份待接收的会话包，`key` 是它在移交存储上的对象 key。 */
 export interface SessionHandoffPendingItem {
-  attachmentId: number
+  key: string
   sid: string
   from: string
-  to: string
   name: string
 }
 
@@ -262,7 +262,7 @@ export type WebviewToExtension
     | { type: 'handoff/request-reject', issueNumber: number }
     | { type: 'session-handoff/users' }
     | { type: 'session-handoff/start', sessionId: string, to: string }
-    | { type: 'session-handoff/accept', attachmentId: number }
+    | { type: 'session-handoff/accept', key: string }
     | { type: 'session-handoff/refresh' }
     | { type: 'dependency/set', issueNumber: number, prerequisiteNumber: number }
     | { type: 'dependency/clear', issueNumber: number, prerequisiteNumber: number }