Easily done.

There are (at least) two ways to do it:

1) Modify GalCiv3GlobalDefs.xml

add:

  <GlobalCombatMods>
   <EffectType>StrategicRepair</EffectType>
   <Target>
    <TargetType>Ship</TargetType>
    <ShipHullType>Tiny</ShipHullType>
   </Target>
   <BonusType>Flat</BonusType>
   <Value>1</Value>
  </GlobalCombatMods>

etc, for the other hull types. This has a high chance of breaking on updates, because GlobalDefs contains so much.

Note: There's already a general StrategicRepair of 1, so you don't actually need to have one for tiny, for your numbers

2) Modify ShipHullStatDefs.xml. Download my version if you want to take a look at it, or use it: https://www.dropbox.com/s/4xoqkvnj7teopw6/Ave%27s%20Ship%20Repair%20Mod.7z?dl=0

For each hull size add in the relevent StrategicRepair, eg for Huge:

 <Stats>
      <EffectType>StrategicRepair</EffectType>
      <Target>
        <TargetType>Ship</TargetType>
      </Target>
      <BonusType>Flat</BonusType>
      <Value>4</Value>
 </Stats>

etc, for other hull types. This will only break if ship hull stats change format (unlikely), though it could cause balancing to not take effect until the mod is updated.

Note: Again, there's already a general repair of 1, so that flat 4 makes it repair 5 per turn.