Add chained collect node

[JPPhoto]

Summary

Feature + fix: enhanced the built-in collect node to support chaining via collect.collection while preserving existing multi-collect.item behavior.

Why:

• Enable native Collect -> Collect workflows (similar to @skunkworxdark's collection_tools) without breaking existing graphs.
• Keep collector type safety intact across chained and mixed connection order scenarios.
• Align frontend connection validation with backend graph validation.

How:

• Backend (invokeai/app/services/shared/graph.py):
  • collect updated to version="1.1.0".
  • Exposed collection as a real connection input.
  • Kept multi-input behavior for item, single-input behavior for collection.
  • Updated collect input preparation to merge upstream collections + local items.
  • Strengthened collector type resolution for:
    • chained collectors,
    • Any-only collector inputs,
    • union collection annotations containing list branches (T | list[T] | None).
• Frontend:
  • Unhid collect.collection in schema parsing.
  • Updated collect type inference utility to resolve type through collection chains.
  • Updated node util test fixture for collect input typing.
• Also fixed Ruff lint in graph_bench.py (list(map(...)) change).

Related Issues / Discussions

https://discord.com/channels/1020123559063990373/1130288930319761428/1477387080966471802

QA Instructions

Backend:

1. Run:
   • pytest -q tests/test_node_graph.py -k "collector or iterate_accepts_collection or iterate_validates_collection_inputs_against_iterator_outputs"
2. Confirm collector-chain and type mismatch tests pass, including:
   • late-added upstream mismatch rejection,
   • Any-only collector -> iterate acceptance,
   • union collection input mismatch rejection.

Frontend:

1. Run:
   • cd invokeai/frontend/web && pnpm run lint:tsc
   • cd invokeai/frontend/web && node_modules/.bin/vitest run src/features/nodes/store/util/getCollectItemType.test.ts src/features/nodes/store/util/validateConnection.test.ts
2. Confirm no TS errors and tests pass.

Merge Plan

Checklist

• The PR has a short but descriptive title, suitable for a changelog
• Tests added / updated (if applicable)
• ❗Changes to a redux slice have a corresponding migration
• Documentation added / updated (if applicable)
• Updated What's New copy (if doing a release after this PR)