refactor: improve docs and types throughout

[nberlette]

• refactor(internal): drop the unused LCG module from the old impl
• refactor: remove old top-level entrypoints for types, guards, constants modules
• refactor: move ./constants.ts entry point to ./constants/mod.ts
• refactor: move ./guards.ts entry point to ./guards/mod.ts
• chore: remove ieee754 re-export from root module
• refactor: move ./types.ts entry point to ./types/mod.ts
• docs(types): add docs to every export in types/integer
• docs(types): update tags in finite and safe-integer
• fix(guards): fix typo in predicate signature