do not prefer ?? over || with boolean/nullish union

[lukasvice]

Configure ignorePrimitives for prefer-nullish-coalescing

The @typescript-eslint/prefer-nullish-coalescing rule is already enabled via strictTypeChecked.

This change adds ignorePrimitives: { boolean: true } to allow || for boolean union types (boolean | undefined, boolean | null), where || is often the intended operator.

For example, with optional React props typed as boolean | undefined:

// ✅ Allowed now — || intentionally treats both false and undefined as falsy
disabled={submitting || disabled}

Using ?? here would change the semantics: submitting ?? disabled returns false when submitting is false, while || falls through to disabled. For boolean flags, treating false and undefined the same way is typically what you want.

The rule still enforces ?? for non-boolean nullable types, where falsy coercion is usually a bug:

// ❌ Still an error — "" and 0 would incorrectly fall through with ||
const name = user.name || "Anonymous";
const count = response.count || 0;

// ✅ Correct
const name = user.name ?? "Anonymous";
const count = response.count ?? 0;

See https://typescript-eslint.io/rules/prefer-nullish-coalescing for reference.