feat: deduplicate subgraph node IDs on workflow load (experimental) (#8762)

## Summary

Add `ensureGlobalIdUniqueness` to reassign duplicate node IDs across
subgraphs when loading workflows, gated behind an experimental setting.

## Changes

- **What**: Shared `LGraphState` between root graph and subgraphs so ID
counters are global. Added `ensureGlobalIdUniqueness()` method that
detects and remaps colliding node IDs in subgraphs, preserving root
graph IDs as canonical and patching link references. Gated behind
`Comfy.Graph.DeduplicateSubgraphNodeIds` (experimental, default
`false`).
- **Dependencies**: None

## Review Focus

- Shared state override on `Subgraph` (getter delegates to root, setter
is no-op) — verify no existing code sets `subgraph.state` directly.
- `Math.max` state merging in `configure()` prevents ID counter
regression when loading subgraph definitions.
- Feature flag wiring: static property on `LGraph`, synced from settings
via `useLitegraphSettings`.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8762-feat-deduplicate-subgraph-node-IDs-on-workflow-load-experimental-3036d73d36508184b6cee5876dc4d935)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Amp <amp@ampcode.com>
Co-authored-by: GitHub Action <action@github.com>

src/schemas/apiSchema.ts

@@ -288,6 +288,7 @@ const zSettings = z.object({
   'Comfy.Graph.CanvasInfo': z.boolean(),
   'Comfy.Graph.CanvasMenu': z.boolean(),
   'Comfy.Graph.CtrlShiftZoom': z.boolean(),
+  'Comfy.Graph.DeduplicateSubgraphNodeIds': z.boolean(),
   'Comfy.Graph.LiveSelection': z.boolean(),
   'Comfy.Graph.LinkMarkers': z.nativeEnum(LinkMarkerShape),
   'Comfy.Graph.ZoomSpeed': z.number(),