chore(crucible): drop dead NWN_ROOT rule; auto-detect is the forward rule

docs/consumer-contract.md

@@ -36,17 +36,6 @@ container:
 
 ~~No host install, no `$HOME` layout, no developer machine assumptions.~~
 
-## `NWN_ROOT` rule
-
-Crucible **never guesses `NWN_ROOT` from `$HOME`** (this was a deploy-notes
-pain point). The NWN install/data root is passed explicitly:
-
-- env `NWN_ROOT=/path/to/nwn`, or
-- flag `--nwn-root /path/to/nwn`.
-
-A builder that needs `NWN_ROOT` and receives neither must fail closed with a
-clear message, not fall back to a home-directory default.
-
 ## Determinism
 
 Same inputs → identical output bytes. Consumers may checksum artifacts across