The narrowing test for `isStructureKind` had `const candidate: string =
'medico_social'`, which ESLint's `@typescript-eslint/no-inferrable-types`
correctly flags as trivially-inferred.
The naive fix - dropping the annotation - would let TypeScript infer
the literal type `'medico_social'`, which is already a StructureKind
subtype. The narrowing check would then be vacuous (TypeScript already
knows the value is a kind, the runtime guard has nothing to prove).
Fix: round-trip through `String()` to widen the literal to `string`.
TypeScript infers `string` for `String(...)` return; no annotation
needed; the narrowing test stays meaningful.
CI lint target on portal-bff now passes 0 errors. The 13 remaining
warnings (non-null assertions in principal-extractor.spec, unused
underscored params in rate-limit.middleware, etc.) are pre-existing
and not in scope for this fix.
Julien Gautier