fix(smolmachines): consolidate virtiofs mounts to stay within libkrun limit

libkrun limits total mounts + port-mappings to 5. With all three
sidecar daemons active (egress, git-gate, supervise), the prior
layout used 3 mounts + 3 ports = 6, causing the VM to crash at boot
with krun_start_enter returned -22.

Merge the egress confdir and git-gate scripts into a single staging
directory mounted at /bot-bottle-data/ with egress/ and git-gate/
subdirectories, reducing to 2 mounts + 3 ports = 5. Also clean up
leftover VMs before creating new ones to handle interrupted teardowns.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/unit/test_smolmachines_egress_apply.py

@@ -18,7 +18,7 @@ class TestFetchCurrentRoutes(unittest.TestCase):
             self.assertEqual("routes", egress_apply.fetch_current_routes("dev-abc"))
         exec_.assert_called_once_with(
             "bot-bottle-sidecars-dev-abc",
-            ["cat", "/etc/egress/routes.yaml"],
+            ["cat", "/bot-bottle-data/egress/routes.yaml"],
         )
 
     def test_read_failure_raises_apply_error(self):