feat(ACTIVITY-WP-0029): inventory callers, retarget sweep, bound execution

Map every State Hub/core-hub caller to a post-retirement owner. Keep the
15-minute sweep schedule here and point the engine at repo-manager
(State Hub dual-run by default, REPO_MANAGER_URL when present). Publish
GET /execution/semantics and 410 workplan launch routes so State Hub
/execution/* is not re-homed as a task database. T03 still waits on
HUB-WP-0004.

src/activity_core/api.py

@@ -11,6 +11,7 @@ Endpoints:
   DELETE /activity-definitions/{id}      — delete
   POST   /activity-definitions/{id}/trigger — manual one-shot run
   GET/POST /ops/...                      — operator console (inventory, status, control)
+  GET    /execution/semantics            — launch/ops_run contract (ACTIVITY-WP-0029)
 
 Schedule lifecycle:
   - POST/PUT with trigger_type='cron' upserts a Temporal Schedule.
@@ -40,6 +41,7 @@ from temporalio.api.workflowservice.v1 import GetSystemInfoRequest
 from temporalio.client import Client
 
 from activity_core.models import ActivityDefinition, CronTriggerConfig
+from activity_core.execution_api import router as execution_router
 from activity_core.ops_api import bind_ops_deps, router as ops_router
 from activity_core.ops_runs_api import bind_ops_runs_deps, router as ops_runs_router
 from activity_core.orm import ActivityDefinition as ActivityDefinitionRow, EventType as EventTypeRow
@@ -85,6 +87,7 @@ app = FastAPI(title="activity-core API", lifespan=lifespan)
 app.include_router(webhook_router)
 app.include_router(ops_router)
 app.include_router(ops_runs_router)
+app.include_router(execution_router)
 
 
 def _get_db() -> async_sessionmaker[AsyncSession]: