feat: add confirmed Take down stack action with optional volume removal (#1599)

* feat: add confirmed Take down stack action with optional volume removal

Expose Take down in the stack header and sidebar with a confirmation dialog
that runs compose down while keeping the stack definition on disk. Optional
volume removal is gated by node capability and stack:deploy permission, with
remote gateway preflight before proxying removeVolumes requests.

Closes #1582

* fix: reset take-down volume checkbox when dialog closes

* test: align getStackMenuVisibility assertions with showTakeDown key

getStackMenuVisibility now returns a fifth lifecycle flag, showTakeDown,
but three exhaustive toEqual assertions still listed only the prior four
keys and failed. Add the expected showTakeDown value to each: true for
the partial and exited running-stack cases, false for the self stack.

* test: cover Take down visibility for running non-self stacks

The getStackMenuVisibility assertions exercised the partial and exited
branches and the self-stack guard, but not the raw === 'running' literal
that drives showTakeDown for a normal running stack. Add a case so a
regression dropping 'running' from that check is caught.

* fix: drop Take down from header overflow and wire activity shortcut

Remove duplicate Take down from More actions.

Keep inline button when running, sidebar menu, and Cmd+ArrowDown.

Record stack_taken_down in activity on successful POST /down.

docs/openapi.yaml

@@ -1420,10 +1420,16 @@ paths:
       operationId: downStack
       tags: [Stacks]
       summary: Tear down stack
-      description: Runs `docker compose down` for the stack, removing containers and networks. Requires `stack:deploy` permission.
+      description: Runs `docker compose down` for the stack, removing containers and networks. The stack definition remains on disk. Requires `stack:deploy` permission. Pass `removeVolumes=true` to also remove compose volumes when the node advertises the `stack-down-remove-volumes` capability.
       parameters:
         - $ref: "#/components/parameters/stackName"
         - $ref: "#/components/parameters/nodeId"
+        - name: removeVolumes
+          in: query
+          required: false
+          schema:
+            type: boolean
+          description: When `true`, runs `docker compose down --volumes`. Only honored when the target node advertises `stack-down-remove-volumes`.
       responses:
         "200":
           description: Command started.
@@ -1436,6 +1442,12 @@ paths:
                   status:
                     type: string
                     example: Command started
+        "400":
+          description: Volume removal requested on a node that does not support it.
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/Error"
         "403":
           $ref: "#/components/responses/Forbidden"
         "500":