v2.0.0

seesaw-tgg 2.0.0

One generation, one rule format, two languages.

The first engine generation is removed. What remains is one system: the
rule format with a single loading path (parse, validate, lower), the
model with value-free structural identity, the creation plan, the
delta-local cascade. No negative application conditions, no typed
edges, no generation numbers in modules, files or identifiers.

Rust and Java read the same format and lower it to the same plans,
shown on three levels of comparison.

cargo test 150 green, mvn test 69 green.