Group mode menu mutates node.mode directly instead of dispatching a command batch

Group mode changes from the canvas context menu mutate `node.mode` directly instead of producing a command batch, which ADR 0003 / ADR 0008 require for entity state changes.

```ts
// src/extensions/core/groupOptions.ts
function setNodeMode(node: LGraphNode, mode: LGraphEventMode) {
node.mode = mode
node.graph?.change()
}
```

Each menu callback calls this once per node in the group, so setting the mode on an N-node group emits N separate non-serializable updates. There is no atomic undo, no replay, and nothing transmittable over CRDT — selecting "Bypass Group Nodes" on a 10-node group takes 10 undo steps to reverse.

Wanted: one replayable command batch per menu action, covering every node in the group.

Surfaced by CodeRabbit on #15366 (https://github.com/Comfy-Org/ComfyUI_frontend/pull/15366#discussion_r-groupoptions). It is pre-existing on `main` — #15366 only re-typed the `mode` parameter and collapsed the duplicated menu branches, so fixing it there would have turned a behaviour-preserving refactor into a behaviour change. Split out here instead.

Same pattern likely applies to other bulk node-mode paths (single-node bypass, keybinding-driven mode toggles) — worth checking them in the same pass.

Start in src/extensions/core/groupOptions.ts at setNodeMode and inspect ADR 0003, ADR 0008, and the command-batch patterns used by the menu callbacks. Trace the existing command APIs before changing the group action; done means one replayable, serializable batch covers all selected nodes and supports atomic undo, replay, and CRDT transmission.

Written by the indexing model from the issue text.