Changes in version 0.0.0.9000                      

  - Initial version.
  - A lean knitr engine (eng_lean()) that compiles and checks Lean 4
    chunks against a lake project, accumulating definitions across
    chunks in a session and showing per-chunk output deltas. A failing
    Lean check fails the render.
  - Chunk options: eval, error, session, timeout, and axioms (appends
    #print axioms <name> to assert a theorem carries no stray axioms /
    sorry).
  - install_lean() provisions a Lean toolchain via elan, à la
    torch::install_torch().
  - Session helpers, find_lake(), leanknit_available(), lean_version(),
    lean_sitrep(), and leanknit_example_project().