feat(chv-muse-p1): 常驻 VM + WarmPool 扶正 + 气球 + vsock，对齐 Muse

每用户一台常驻 VM（暂停态，resume 到 SSH 5 秒内为待验证目标），
池空/失败回落冷启动；CHV 配置加 virtio-balloon + free-page-reporting
与 vsock notify 最小实现（SSH 仍是命令通道与就绪判定）。
新模块 resident_pool.py / vsock.py + 客内 vsock_notify.py；
_config 增加 CHV_RESIDENT_IDLE_MINUTES / CHV_BALLOON / CHV_VSOCK；
worker_adapter 接常驻孤儿清理 facade；ADR-17 差距表见
docs/chv-muse-p1-gap.md。

恢复收尾（分离后回归，见 gap.md §4）：VmDeathTest 死亡模拟改杀
实际跑命令的 VM；两处冷路径旧测试显式关常驻；_balloon_vsock_payload
与 listen_notify 拆到 50 行内；resident_pool.py:208 mypy 修掉。
executor.py out 未注解与 marker_tools.py:142 是基线旧错，未动。

测试：全量 cloud 套件 1934 OK（skipped=8）；mypy 在改动文件上
干净（仅基线旧错 4 处）。真机验证待第三棒让出 WSL 测试机。

cloud/tests/test_chv_arch_maint_fe.py

@@ -31,6 +31,7 @@ try:
     from cloud.chv.compat215 import REPLACEMENT_POINTS
     from cloud.chv.compat215 import resolve_inside, tmpfs_isolated
     from cloud.chv.config import _assemble_chv_config
+    from cloud.chv.config import _balloon_vsock_fragment
     from cloud.chv.config import _base_fragment
     from cloud.chv.config import _disk_fragment
     from cloud.chv.config import _network_fragment
@@ -48,6 +49,7 @@ except ImportError:
     from cloud.chv.compat215 import REPLACEMENT_POINTS
     from cloud.chv.compat215 import resolve_inside, tmpfs_isolated
     from cloud.chv.config import _assemble_chv_config
+    from cloud.chv.config import _balloon_vsock_fragment
     from cloud.chv.config import _base_fragment
     from cloud.chv.config import _disk_fragment
     from cloud.chv.config import _network_fragment
@@ -76,6 +78,8 @@ EXPECTED_FIELDS = {
     "snapshot_max_total_gb", "snapshot_retention_days",
     "snapshot_dir", "allow_remote_snapshot", "snapshot_url",
     "task_timeout", "api_timeout", "ready_timeout", "ready_interval",
+    # P1-B（feat-chv-muse-p1）：气球/vsock 三字段。
+    "balloon", "vsock", "vsock_cid",
 }
 
 
@@ -249,13 +253,15 @@ class ConfigFragmentsTest(unittest.TestCase):
     def test_fragment_keys_disjoint_and_union_is_field_set(self):
         frags = [_base_fragment({}, {}), _ssh_fragment({}, {}),
                  _network_fragment({}, {}), _quota_fragment({}),
-                 _disk_fragment({}), _timeout_fragment({}, {})]
+                 _disk_fragment({}), _timeout_fragment({}, {}),
+                 # P1-B：新片段加入并集断言（字段 38 → 41）。
+                 _balloon_vsock_fragment({})]
         seen = set()
         for frag in frags:
             self.assertFalse(seen & set(frag), "片段键重叠")
             seen |= set(frag)
         self.assertEqual(seen, EXPECTED_FIELDS)
-        self.assertEqual(len(EXPECTED_FIELDS), 38)
+        self.assertEqual(len(EXPECTED_FIELDS), 41)
 
     def test_defaults_and_overrides(self):
         cfg = build_chv_config({}, {})