Enforced by Biome w/ pre-commit hooks (simple-git-hooks + lint-staged).

• Linter: noUnusedImports/noUnusedVariables error; useImportType error; noExplicitAny error; noNonNullAssertion error, off in test files—narrow or guard instead (formatting is biome.json's job—the hook rewrites it)
• TypeScript: Full strict (noUncheckedIndexedAccess, exactOptionalPropertyTypes, noImplicitOverride)
• Imports: import type for type-only imports (useImportType, error)