✨ feat(vscode): 新增第五种工单会话「原型会话」

照测试会话那条链路补一份 prototype：

- 消息与路由：session/start-prototype、session/resume-prototype、
  issue/update-prototype-profile-path，都进只读门禁
- 会话：handleStartPrototypeSession / handleResumePrototypeSession，
  终端名 issue-N-原型；cwd 有 worktree 用 worktree、没有退主仓库根
  （原 resolveTestSessionCwd 改名 resolveWorktreeOrRootCwd 两种会话共用）
- 不要求有 PR，任何阶段都能起；前置工单锁仍然拦
- 提示词：新增 prompts/prototype.md，设置里可改，占位符 {issueNumber}
- profile：工单级 prototypeProfilePath > 设置里的原型默认 profile >
  内置默认，与其它会话互不回退
- 状态字段 prototypeSessionId / prototypeProfilePath / prototypeTabOpen
  贯通 gitea、youtrack、本机 state 与移交包
- 详情面板加「原型会话id」「原型配置文件」两行，设置面板加对应两项

Claude-Session: https://claude.ai/code/session_01Kgmb1LvrPmFX3NoUDB4zZC

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

@@ -34,6 +34,8 @@ interface BottomTabsProps {
   onStartReviewSession: (issueNumber: number) => void
   onStartTestSession: (issueNumber: number) => void
   onResumeTestSession: (sessionId: string, issueNumber: number, cwd?: string) => void
+  onStartPrototypeSession: (issueNumber: number) => void
+  onResumePrototypeSession: (sessionId: string, issueNumber: number, cwd?: string) => void
   onOpenFile: (path: string) => void
   onImplement: (issueNumber: number, planFile: string, profilePath?: string, sessionId?: string) => void
   onOpenPr: (pr: string) => void
@@ -45,13 +47,14 @@ interface BottomTabsProps {
   onDeleteIssue?: (issueNumber: number) => void
   onCloseIssue: (issueNumber: number) => void
   onResetToTodo: (issueNumber: number) => void
-  onCloseSessionTab: (issueNumber: number, kind: 'brainstorm' | 'implement' | 'review' | 'test') => void
+  onCloseSessionTab: (issueNumber: number, kind: 'brainstorm' | 'implement' | 'review' | 'test' | 'prototype') => void
   onContinueBrainstorm: (issueNumber: number) => void
   onClearBrainstormSession: (issueNumber: number) => void
   onUpdateAutoReview: (issueNumber: number, value: boolean) => void
   onUpdateProfilePath: (issueNumber: number, profilePath: string) => void
   onUpdateBrainstormProfilePath: (issueNumber: number, brainstormProfilePath: string) => void
   onUpdateTestProfilePath: (issueNumber: number, testProfilePath: string) => void
+  onUpdatePrototypeProfilePath: (issueNumber: number, prototypeProfilePath: string) => void
   onOpenLogs: () => void
   me?: string
   /** Gitea login → 头像 data URI。 */
@@ -134,6 +137,8 @@ export function BottomTabs(props: BottomTabsProps) {
             onStartReviewSession={props.onStartReviewSession}
             onStartTestSession={props.onStartTestSession}
             onResumeTestSession={props.onResumeTestSession}
+            onStartPrototypeSession={props.onStartPrototypeSession}
+            onResumePrototypeSession={props.onResumePrototypeSession}
             onOpenFile={props.onOpenFile}
             onImplement={props.onImplement}
             onOpenPr={props.onOpenPr}
@@ -152,6 +157,7 @@ export function BottomTabs(props: BottomTabsProps) {
             onUpdateProfilePath={props.onUpdateProfilePath}
             onUpdateBrainstormProfilePath={props.onUpdateBrainstormProfilePath}
             onUpdateTestProfilePath={props.onUpdateTestProfilePath}
+            onUpdatePrototypeProfilePath={props.onUpdatePrototypeProfilePath}
             profiles={props.profiles}
             onOpenLogs={props.onOpenLogs}
             me={props.me}