Stacks: remote stacks editable from the hub, .env editing, deploy diff, image update checks; a gone container says so

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

PLAN.md

@@ -213,9 +213,17 @@ something long in one, switch away and back, refresh — it's all still there.
   and the compose labels stay exactly as deployed (verified: labels identical after a
   redeploy). Save validates with `compose config` first, keeps the previous file as
   `<file>.hamlab-bak`, and never deploys by itself. A stack deployed from another host
-  (Dockhand on `core` driving `grid` over tcp) has no file on that machine: listed
-  read-only, saying so — edit those from the machine that holds the file. Removing
-  containers, images and volumes is still absent.
+  (Dockhand on `core` driving `grid` over tcp) has no file on that machine, so the node
+  alone lists it read-only — but **the hub fills that in** (`hubStacks`): asked about a
+  node, it resolves the files on itself and runs compose here with `DOCKER_HOST` pointed
+  at the node's `tcp://…:2375`, the way it was deployed; the task runs on the hub and the
+  node's page follows it. Also per stack: every file it was deployed from (chips), its
+  **`.env`** (values masked until "Reveal and edit"; validated in place, put back if
+  compose objects), **what Deploy would change** (a line diff against the copy kept at the
+  last deploy from here, `<file>.hamlab-deployed`, else the copy the last save replaced;
+  `.env` values never shown), and **image update checks** — asked for, never polled, since
+  each is a registry request Docker Hub counts; remembered six hours. A save refuses a
+  file changed on disk meanwhile. Removing containers, images and volumes is still absent.
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