feat(freeze): no authors in the config, no author check

A repository that takes commits from people it cannot list has no way
to freeze a range today: a null `authors` falls back to
`git config user.email`, so every foreign author or committer fails.
Null, or no key, now means neither is checked; the freeze warns that it
did not check them and records `authors` as null. A list is checked as
before. An empty list, which no commit could pass, is a config error
that points at null.
Released as 1.1.0.

README.md

@@ -41,7 +41,7 @@ crafter-review config        # edit .review-gates/config.json until it prints no
 
 `.review-gates/config.json` is committed. It says:
 
-- what `freeze` checks: `authors`, `aiTrailers`, `requireSigned`, and the branch a range is measured against (`base`, `rangeFrom`);
+- what `freeze` checks: `authors` (null: not checked), `aiTrailers`, `requireSigned`, and the branch a range is measured against (`base`, `rangeFrom`);
 - `modes.<name>`: the kind of artifact, the lenses it runs and their effort. Every lens is off until a mode lists it; `run --mode` picks one;
 - `lenses.<name>`: the environment a lens gets (`none`, `browser`, `supabase` or `browser+supabase`) and, if the repository has one, its `section` - a file of this repository's own appended to the lens's charter;
 - `functional`, `slots`, `supabase`: how the application is started and reached, one stack or several, and where its database answers;