fix(types): add Unit x array overloads for multiply and dotMultiply

[abhijeet117]

Summary

multiply and dotMultiply support multiplying a Unit by an array of numbers at runtime (each entry scales the unit), but no declared overload expressed it: multiply(unit, array) fell through to the MathType catch-all and dotMultiply(unit, array) resolved to the generic collection overload returning the array's own element type. This adds Unit x MathNumericType[] overloads in both argument orders returning Unit[], matching the runtime result.

Testing

A scratch file calling all four forms (multiply/dotMultiply with the unit on either side) failed tsc --strict before the change with "Type 'MathType' is not assignable to type 'Unit[]'" and "'number[]' is not assignable to type 'Unit[]'", and compiles cleanly after. Runtime behavior is unchanged; the outputs match the examples in #3660. eslint passes on types/index.d.ts.

Checklist

• bug reproduced before fix
• root cause identified
• bug fixed
• tests passed