Scaffold orchestrator-api Python project (uv, ruff, pyright, pytest)

[Ryan-Atkinson87]

Spec: §13 (Tech stack), §2 (High-level architecture); CLAUDE.md "Tech stack & commands".

Establish the backend project skeleton so every subsequent Foundations issue has a home and a working toolchain. No engine logic yet — just the scaffold and the gates that all later PRs run against.

Acceptance criteria

• orchestrator-api/ created with a pyproject.toml managed by uv (Python 3.13).
• uv lockfile (uv.lock) committed.
• Base package layout (e.g. an app/ package with __init__.py).
• ruff configured for lint and format; uv run ruff check . and uv run ruff format --check . run clean.
• pyright configured; uv run pyright runs clean on the skeleton.
• pytest configured; uv run pytest runs and passes a trivial placeholder test.
• Dev commands documented (orchestrator-api/README.md or the root README).

Dependencies

None — this is the first issue in the project.