tatara-platform-checks — platform-wide invariant runner.
Each Invariant is a typed check function over the registered
catalog. The runner walks them all, collecting pass/fail for
every keyword. No invariant assumes any specific domain — they
all read from the global registries directly, so adding a new
catalog domain inherits the full suite for free.
Adding a new invariant is a single function + an entry in
default_invariants(). The compounding curve flattens once
more: new layers describe themselves; new invariants describe
the platform-wide properties those layers must satisfy.