refactor: enforce single-worker control plane

tests/fixtures/architecture/dependency-baseline.json

@@ -13,8 +13,8 @@
     "runtime_to_db": [],
     "workflow_to_db": []
   },
-  "edge_count": 6076,
-  "edge_sha256": "98150e02051b59ca341c62a71ec050aaa3807b6f20eba40a3d1cda76682503d1",
+  "edge_count": 6080,
+  "edge_sha256": "57d091e93986ca0d8e8a93a300c3c6d0eb0c2bfe92fda747cffd829cc3c25cab",
   "edges": [
     "app -> app.runtime",
     "app -> app.runtime.compat",
@@ -3507,6 +3507,7 @@
     "app.doctor.checks -> app.doctor.models",
     "app.doctor.checks -> app.runtime",
     "app.doctor.checks -> app.runtime.config",
+    "app.doctor.checks -> app.runtime.topology",
     "app.doctor.formatters -> app.doctor",
     "app.doctor.formatters -> app.doctor.models",
     "app.doctor.runner -> app.adapters",
@@ -3637,6 +3638,7 @@
     "app.main -> app.factory",
     "app.main -> app.runtime",
     "app.main -> app.runtime.config",
+    "app.main -> app.runtime.topology",
     "app.main -> app.startup",
     "app.main -> app.startup.database_initializer",
     "app.modules -> app.runtime",
@@ -5745,10 +5747,12 @@
     "app.startup.lifecycle -> app.chain",
     "app.startup.lifecycle -> app.chain.system",
     "app.startup.lifecycle -> app.db",
+    "app.startup.lifecycle -> app.db.engine",
     "app.startup.lifecycle -> app.runtime",
     "app.startup.lifecycle -> app.runtime.config",
     "app.startup.lifecycle -> app.runtime.log",
     "app.startup.lifecycle -> app.runtime.state",
+    "app.startup.lifecycle -> app.runtime.topology",
     "app.startup.lifecycle -> app.startup",
     "app.startup.lifecycle -> app.startup.cache_initializer",
     "app.startup.lifecycle -> app.startup.command_initializer",
@@ -6093,7 +6097,7 @@
     "app.workflow.actions.transfer_file -> app.workflow",
     "app.workflow.actions.transfer_file -> app.workflow.actions"
   ],
-  "module_count": 753,
+  "module_count": 754,
   "modules": [
     "app",
     "app.adapters",
@@ -6751,6 +6755,7 @@
     "app.runtime.scheduling",
     "app.runtime.state",
     "app.runtime.thread",
+    "app.runtime.topology",
     "app.scheduler",
     "app.schemas",
     "app.schemas.agent",