Minimal ReActV2 normalized adapter port

[isaacbmiller]

Summary

Replaces #59 with a downscoped four-commit stack on top of cmpnd/main.

Key pieces:

• preserves the public adapter format() / format_demos() contract while keeping LMRequest as the adapter-to-LM boundary
• adds ToolCallResults and native tool result message rendering without broadening History normalization
• replays native tool-call history as assistant tool-call parts plus tool role result messages
• adds ReActV2 with native tool-call support, submit fallback, error observations, and history recording

Commit stack:

1. refactor(adapter): preserve public formatting through LMRequest
2. feat(adapter): add tool call result types
3. feat(adapter): replay tool call history
4. feat(predict): add ReActV2

Validation

• uv run --frozen ruff check dspy/adapters/base.py dspy/adapters/types/tool.py dspy/predict/reactv2.py tests/adapters/test_adapter_base.py tests/adapters/test_chat_adapter.py tests/adapters/test_tool.py tests/predict/test_reactv2.py
• uv run --frozen pytest -q --tb=short tests/adapters/test_adapter_base.py tests/adapters/test_chat_adapter.py tests/adapters/test_json_adapter.py tests/adapters/test_tool.py tests/predict/test_reactv2.py
  • 147 passed
• uv run --frozen pytest -q --tb=short
  • 924 passed, 323 skipped, 2 xfailed, 50 warnings

Note: local docs/reports/ files remain intentionally untracked and are not included in this PR.