Cache keys drive rebuilds

When using uv to build Python extensions via PEP 517 (e.g., maturin), ensure cache invalidation is keyed to the actual build inputs. Configure tool.uv.cache-keys so builds rerun only when the underlying sources for the compiled artifact change—especially Rust sources and Cargo manifests—rather than rebuilding whatever project owns the root pyproject.toml.

Apply this by:

• Adding Rust build inputs to tool.uv.cache-keys (e.g., src/**/*.rs, Cargo.toml, Cargo.lock, or the whole crate dir like rustbpe/**).
• Including the crate in the workspace so uv associates changes with the correct package (e.g., rustbpe = { workspace = true }).
• Verifying uv sync / uv run actually rebuilds the intended artifact when Rust code changes.

Example:

[tool.uv]
# Invalidate build cache when Rust crate inputs change
cache-keys = [
  { file = "pyproject.toml" },
  { file = "rustbpe/**" },
  # alternatively, more targeted keys like:
  # { file = "src/**/*.rs" },
  # { file = "Cargo.toml" },
  # { file = "Cargo.lock" }
]

# Ensure the crate is part of the workspace so the right package rebuilds
[rustbpe]
# (or in the relevant uv sources section)
# rustbpe = { workspace = true }