feat(v0.1): add mgr session PVC lifecycle for true session state persistence

PR B for #770: mgr/session-pvc.ts + server endpoints + selftest.

- 新模块 src/mgr/session-pvc.ts: createSessionPvc / getSessionPvcSummary / deleteSessionPvc / refreshSessionPvcSummary / runSessionStorageGc / startSessionStorageGcLoop
- Server 增量 4 个 endpoint:
  * POST /api/v1/sessions: 创建 session 同步创建 PVC
  * GET /api/v1/sessions/:id/storage: 查询 PVC 摘要
  * DELETE /api/v1/sessions/:id/storage: 删 PVC + storage_kind=evicted
  * POST /api/v1/sessions/:id/storage/refresh: runner 上报 PVC 摘要
  * POST /api/v1/sessions/storage/gc: 手动触发 GC
- mgr SA RBAC 已在 PR A 增加；manager server 不直连 Kubernetes API（kubectl 由 mgr 容器内执行）
- SessionRecord 增量 storageKind / storagePvcName / storageNamespace / storageSizeBytes / storageFilesCount / storageSha256 / storageUpdatedAt / storagePvcPhase / storageEvictedAt / codexRolloutSubdir
- kubernetes-runner-job 短路：run 引用 evicted session 时直接返回 session-store-evicted，不创建 runner Job
- KubectlHandler 可注入，selftest 覆盖 create / summary / refresh / eviction / gc / REST 路径
- GC loop 默认 5min（AGENTRUN_SESSION_GC_INTERVAL_MS 可调）

runner / backend / HWLAB adapter 在 PR C / PR D 落地。

src/mgr/kubernetes-runner-job.ts

@@ -75,6 +75,12 @@ export async function createKubernetesRunnerJob(options: { store: AgentRunStore;
   }
   if (isTerminalRunStatus(run.status)) throw new AgentRunError(run.failureKind ?? (run.status === "cancelled" ? "cancelled" : "schema-invalid"), `run ${run.id} is already terminal: ${run.status}`, { httpStatus: 409 });
   if (isTerminalCommandState(command.state) || command.state !== "pending") throw new AgentRunError(command.state === "cancelled" ? "cancelled" : "schema-invalid", `command ${commandId} is not pending: ${command.state}`, { httpStatus: 409 });
+  if (run.sessionRef?.sessionId) {
+    const session = await options.store.getSession(run.sessionRef.sessionId);
+    if (session?.storageKind === "evicted") {
+      throw new AgentRunError("session-store-evicted", `session ${session.sessionId} storage has been evicted; create a new sessionId`, { httpStatus: 409, details: { sessionId: session.sessionId, pvcName: session.storagePvcName ?? null, pvcPhase: session.storagePvcPhase ?? null, valuesPrinted: false } });
+    }
+  }
 
   const renderOptions = {
     run,