fix(networking): hold unsafe network deletions and stabilize aggregate reads (#1850)

* fix(networking): hold unsafe network deletions and stabilize aggregate reads

Networking audit hardening:

- Fail closed when deleting unlabeled external networks while any stack
  fails to render or the Docker runtime is unreachable: declarations
  cannot be verified, so the backend 409s with a typed code and the
  inventory table holds the delete affordance instead of letting the
  confirm dialog surprise the operator.
- Bound concurrent compose renders during network delete verification
  with the shared render semaphore and mapWithConcurrency.
- Add a short-TTL memo for the node networking aggregate keyed by node
  and request variant, invalidated eagerly on stack, exposure-intent,
  dossier, and network mutations, with stale-on-error serves flagged as
  degradedCache and surfaced in the overview.
- Resolve node-scoped stack edit permissions against the active node in
  the findings action list.
- Developer-mode debug logs for aggregate serving and delete-guard
  outcomes.

Tests: cache unit suite, hardening integration suite, and component
coverage for the permission threading and delete-affordance holds.

* chore(networking): add missing EOF newline in aggregate cache module

docs/operations/troubleshooting.mdx

@@ -292,6 +292,14 @@ To re-test connectivity after making changes, open **Settings · Infrastructure
 
 ---
 
+## Network deletion is refused while a stack fails to render
+
+**Symptom:** Deleting an external network returns "Cannot verify stack declarations while one or more stacks failed to render." The delete button may also be disabled with a message about render failures.
+
+**Cause:** Sencho checks every stack's effective Compose model before allowing a network delete, so it never removes a network a stack declares as `external:`. When any stack on the node cannot be rendered (usually a YAML error, an unresolved variable, or a broken include), Sencho cannot prove the network is undeclared and refuses the deletion rather than risk removing a network your stacks depend on.
+
+**Fix:** Find which stack cannot render on the Networking page (the Overview tab lists how many stacks failed), then open that stack and check its Anatomy panels: the Networking panel and the deploy preflight check show the Compose error itself. Fix the YAML (an unresolved variable or a broken include produces the same failure) until the model renders again, then retry the deletion. This is a deliberate safety stop, not a malfunction.
+
 ## Cannot delete a system network (bridge, host, none)
 
 **Symptom:** The delete button is missing or disabled for certain networks.