Type guards take `unknown`; walkers/comparators (get/set/isEqual) narrow via
casts; generic defaults and constraints tightened. Truly-idiomatic any-function
constraints and load-bearing type-level any are kept with explanatory comments.
- Add array/async/etc. modules and type tests; migrate to eslint flat config
and composite tsconfig (vitest typecheck enabled).
- Fix PubSub.emit to snapshot listeners before iterating (stable EventEmitter
semantics; avoids invoking listeners added during the same emit).
robonen