fix: merge worker restore into develop host lifecycle

Integrate integration/worker-restore without reviving removed Worker socket/discovery paths. Keep restore candidate allocation and canonical effects deferred until activation, with registry reclamation and observer publication fences on the in-process controller.

Preserve develop BackendJob/provenance, immutable Journal body capture and erasure, and Workdir diagnostics. Adapt obsolete socket fault tests to in-process publication and registry drift boundaries.

Validation: root cargo check; ordinary worker, worker-runtime and standalone package tests; Server restore (43) and Journal (49) filters; mcp/server-api/runtime-api/session-store tests; optional Runtime feature check; OpenAPI and six generated TypeScript checks; Web restore unit tests (15); runner tests (21); fmt, naming and diff checks. Full workspace/Server suites, E2E, live/model and fixture generation not run.

crates/session-store/src/worker_session_store.rs

@@ -194,6 +194,21 @@ impl WorkerSessionStore {
         Ok(store)
     }
 
+    /// Open a current retained Session without creating or migrating anything.
+    /// The live constraint is checked here and again by every later publication;
+    /// attaching the control store itself does not acquire publication authority.
+    pub fn open_existing_with_retention(
+        root: impl Into<PathBuf>,
+        retention: crate::retention::SessionRetentionStore,
+    ) -> Result<Self, StoreError> {
+        let mut store = Self::open_read_only(root)?;
+        if let Some(session) = *store.session_id.lock().unwrap() {
+            retention.ensure_live(session)?;
+        }
+        store.retention = Some(retention);
+        Ok(store)
+    }
+
     fn lock_publication(
         &self,
         session: SessionId,