SmrPlanetStructureType: add typehints
SmrPlanetStructureType: add typehints

* Simplify `hardwareCost` implementation by using the null coalescing
  operator (only the Radar Station costs a Scanner).

smrealms/smr,hemberger/smr,hemberger/smr,hemberger/smr,hemberger/smr,smrealms/smr,smrealms/smr