✨ feat(vscode): 工单挂原型插件，详情面板一键导入 Figma

- prototypeFile 走通 state → Issue → webview 全链路（gitea/youtrack 两个
  loader、两份 KNOWN_STATE_FIELDS、issue/patch、webview types），按 planFile
  同款当共享字段；路径校验换成 .json 版，允许绝对路径
- 详情面板「计划文件」下加「原型插件路径」行：双击开 manifest.json，
  行尾按钮「在 Figma 中导入并打开」；没挂插件时只显示空态
- src/figma/：把 manifest 写进 Figma 桌面版的 localFileExtensions 再拉起
  Figma。坑是 Figma 退出会用内存状态覆盖 settings.json，所以写之前先
  osascript 优雅退出并轮询等它真没了（10s 等不到就让用户手动关，不强杀）；
  写前备份 settings.json.bak-<时间戳>；已导入过就跳过写入直接打开；
  非 macOS 只把路径复制到剪贴板
- webhook 里 spec/plan 的 marker 同步改成表驱动，顺带认第三种 prototype
- 提示词：prototype.md 要求画完挂 marker；brainstorm-continue.md 新增
  {prototypeRef} 占位符，有原型插件时让续聊先读它别从零重画，没有时
  连同整段抹掉

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

vscode/src/panel/messages.ts

@@ -52,7 +52,7 @@ export type ExtensionToWebview
     | { type: 'issues/loaded' }
     | { type: 'issues/update', issues: Issue[], scope: 'mine' | 'all', globalAutoReview: boolean, youtrackConfigured: boolean, me?: string, avatars?: Record<string, string> }
     | { type: 'issues/error', message: string }
-    | { type: 'issue/patch', issueNumber: number, patch: { autoReview?: boolean, specFile?: string, planFile?: string, prDiffFile?: string | null, sessionId?: string | null, implementSessionId?: string | null, reviewSessionId?: string | null, reviewSessionFileExists?: boolean, testSessionId?: string | null, prototypeSessionId?: string | null, pr?: string | null, implementStatus?: 'running' | 'done' | 'failed' | null, column?: IssueColumn, worktreePath?: string | null, prMerged?: boolean, prMergedAt?: string | null, branch?: string | null, color?: string, worktreeExists?: boolean, brainstormTabOpen?: boolean, implementTabOpen?: boolean, reviewTabOpen?: boolean, testTabOpen?: boolean, prototypeTabOpen?: boolean, profilePath?: string | null, brainstormProfilePath?: string | null, testProfilePath?: string | null, prototypeProfilePath?: string | null, assignees?: string[], handoffAttachmentId?: string | null, handoffFrom?: string | null } }
+    | { type: 'issue/patch', issueNumber: number, patch: { autoReview?: boolean, specFile?: string, planFile?: string, prototypeFile?: string, prDiffFile?: string | null, sessionId?: string | null, implementSessionId?: string | null, reviewSessionId?: string | null, reviewSessionFileExists?: boolean, testSessionId?: string | null, prototypeSessionId?: string | null, pr?: string | null, implementStatus?: 'running' | 'done' | 'failed' | null, column?: IssueColumn, worktreePath?: string | null, prMerged?: boolean, prMergedAt?: string | null, branch?: string | null, color?: string, worktreeExists?: boolean, brainstormTabOpen?: boolean, implementTabOpen?: boolean, reviewTabOpen?: boolean, testTabOpen?: boolean, prototypeTabOpen?: boolean, profilePath?: string | null, brainstormProfilePath?: string | null, testProfilePath?: string | null, prototypeProfilePath?: string | null, assignees?: string[], handoffAttachmentId?: string | null, handoffFrom?: string | null } }
     /** 某个会话 id 的开 tab 请求已处理完（开成、复用或被拒都算），webview 据此停掉行内 spinner。 */
     | { type: 'session/tab-settled', sessionId: string }
     | { type: 'issue/pr-diff-summary-done', issueNumber: number }
@@ -203,6 +203,7 @@ export type WebviewToExtension
     | { type: 'session/start-review', issueNumber: number }
     | { type: 'session/start-test', issueNumber: number }
     | { type: 'session/start-prototype', issueNumber: number }
+    | { type: 'prototype/open-in-figma', issueNumber: number, path: string }
     | { type: 'editor/open-file', path: string }
     | { type: 'profiles/list' }
     | { type: 'issue/implement', issueNumber: number, planFile: string, profilePath?: string, sessionId?: string }