Add seeded Text LLM sampling

[JPPhoto]

Summary

Adds controlled seeded sampling to the Text LLM and Text LLM with System Prompt Preset nodes.

• Exposes a validated seed input and bumps both nodes to version 1.1.0.
• Uses invocation-local generators to prevent concurrent requests from interfering with each other's RNG state.
• Preserves varied Expand Prompt results by selecting a fresh seed per request.
• Documents seed behavior and reproducibility boundaries.

Related Issues / Discussions

Discord.

QA Instructions

1. Run:
   pytest -n auto --no-cov tests/backend/text_llm tests/app/invocations/test_text_llm_with_preset.py
2. Confirm all tests pass.
3. Run the same Text LLM node twice with identical inputs and seed; confirm identical output on the same platform.
4. Change the seed; confirm sampling can produce different output.
5. Run concurrent seeded CPU sampling; confirm each request matches its isolated sequence.

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)