✨ feat(vscode): 实施和审查会话行加启动箭头

不用再把卡片拖到「实施中」「审查」列：

- 实施会话id 行在有计划文件且没实施会话时显示 ▶，等同拖进实施中列
- 审查会话id 行在有 PR 时显示 ▶，按 PR 事件那套流程起 codex 审查

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

vscode/src/panel/messages.ts

@@ -193,6 +193,7 @@ export type WebviewToExtension
     | { type: 'session/focus', issueNumber: number }
     | { type: 'session/resume-review', sessionId: string, issueNumber: number, cwd?: string }
     | { type: 'session/resume-test', sessionId: string, issueNumber: number, cwd?: string }
+    | { type: 'session/start-review', issueNumber: number }
     | { type: 'session/start-test', issueNumber: number }
     | { type: 'editor/open-file', path: string }
     | { type: 'profiles/list' }