feat(nix): lint let binding order

src/skills/nix-style/rules/let.md

@@ -15,17 +15,3 @@ Do not apply this rule when a binding names a local constant used to keep siblin
 
 Shared convenience bindings hide dependency direction.
 Explicit references show which value owns a concept and which value consumes it.
-
-## Order `let` bindings by dependency
-
-### Rule
-
-Define a `let` binding before other bindings that reference it.
-Use forward references only for intentional recursion or fixed-point wiring.
-
-### Rationale
-
-Nix permits recursive `let` bindings.
-Top-down dependency order makes ordinary wiring easier to read.
-This rule can become a linter rule because binding references are mechanically detectable.
-