fix: unblock instanceable connectivity store-service install + clean up on delete

Live verification on pic1 of the connectivity v2 multi-instance feature
surfaced four integration bugs that prevented installing any published
connectivity store service (proxy/wireguard-ext/openvpn-client/sshuttle)
and left stale host routing state behind. All four are fixed here:

1. manifest_validator rejected the CI-published `name:tag@sha256:<digest>`
   image form (it required digest-only), while service_store_manager already
   accepted it — so every published store image failed validation. Allow an
   optional tag before the digest, matching service_store_manager.

2. The cell-api image shipped the docker CLI but not the Compose v2 plugin,
   so every `docker compose` ServiceComposer runs (pull/up/down for store
   services) failed with "'compose' is not a docker command". Copy the
   compose plugin binary from the docker-cli stage.

3. service_store_manager.install ran the base compose up for instanceable
   services, whose template still contains ${INSTANCE_ID}/${REDIRECT_PORT}
   (there is no base container — one runs per connection instance). It now
   verifies the image signature but defers the container to connection
   creation for instanceable manifests.

4. delete_connection freed the record/secrets/container but never removed the
   connection's individually-managed `ip rule fwmark->table` or its FORWARD
   kill-switch (apply_routes only flushes the PIC_CONNECTIVITY chains and
   re-adds rules for surviving connections), leaking stale host routing state.
   It now tears both down; added _remove_killswitch.

Verified end-to-end on pic1: two proxy instances allocate distinct
marks/tables/ports (skipping in-use resources), render distinct per-instance
containers, two peers route through distinct instances (per-peer MARK +
REDIRECT), delete is blocked while referenced (409) and cleans its ip rule.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/test_connectivity_connections.py

@@ -110,6 +110,13 @@ class _Base(unittest.TestCase):
         for _svc in ('wireguard-ext', 'openvpn-client', 'tor', 'sshuttle', 'proxy'):
             self.cm.set_installed_service(_svc, {'id': _svc, 'manifest': {}})
         self.cm._save_all_configs()
+        # No test in this module should shell into the WireGuard container. Stub
+        # the exec helpers so host-rule cleanup paths (delete_connection) never
+        # touch real docker/iptables; returncode 1 makes the drain loops stop.
+        self.mgr._wg_ip = MagicMock(
+            return_value=MagicMock(returncode=1, stdout='', stderr=''))
+        self.mgr._wg_iptables = MagicMock(
+            return_value=MagicMock(returncode=1, stdout='', stderr=''))
 
     def tearDown(self):
         shutil.rmtree(self.tmp, ignore_errors=True)
@@ -296,6 +303,42 @@ class TestDeleteConnection(_Base):
         out = self.mgr.delete_connection('conn_nope')
         self.assertFalse(out['ok'])
 
+    def test_delete_removes_host_ip_rule(self):
+        """Deleting a connection must remove its fwmark->table ip rule.
+
+        apply_routes only re-adds rules for surviving connections and only
+        flushes the PIC_CONNECTIVITY chains, so the deleted connection's
+        individually-managed `ip rule` would otherwise leak in cell-wireguard.
+        """
+        res = self.mgr.create_connection('proxy', 'gone', _proxy_cfg())
+        conn = res['connection']
+        mark, table = conn['mark'], conn['table']
+        self.mgr._wg_ip.reset_mock()
+        out = self.mgr.delete_connection(conn['id'])
+        self.assertTrue(out['ok'], out)
+        ip_calls = [c.args[0] for c in self.mgr._wg_ip.call_args_list]
+        self.assertIn(
+            ['rule', 'del', 'fwmark', hex(mark), 'lookup', str(table)],
+            ip_calls,
+        )
+
+    def test_delete_removes_iface_killswitch(self):
+        """An iface-type connection's FORWARD kill-switch is removed on delete."""
+        res = self.mgr.create_connection(
+            'wireguard_ext', 'wgks', {},
+            secrets={'conf': '[Interface]\nPrivateKey = x\n'})
+        conn = res['connection']
+        mark, iface = conn['mark'], conn['iface']
+        self.mgr._wg_iptables.reset_mock()
+        out = self.mgr.delete_connection(conn['id'])
+        self.assertTrue(out['ok'], out)
+        ipt_calls = [c.args[0] for c in self.mgr._wg_iptables.call_args_list]
+        self.assertTrue(
+            any(c[:2] == ['-D', 'FORWARD'] and '--mark' in c and hex(mark) in c
+                and iface in c for c in ipt_calls),
+            ipt_calls,
+        )
+
 
 class TestUpdateConnection(_Base):