Bugfix Update — Shattered Spheres Steam update #1036082

1. Retrofit — the upgrade lookup only matched designs one version ahead, so ships two or more versions behind (or designs overwritten in place) never got a retrofit offer. New ShipDesign.find_retrofit_target() walks the full version-chain ancestry and handles stale in-place overwrites; both the system view and galaxy view retrofit UIs use it, and new GUT tests cover the chain, overwrite, and no-candidate cases.2. Shields — HP scaled with level but slot cost grew faster, so HP-per-slot decreased (the report was right, and worse: even L8+ never overtook L3). Shield totals now scale with slot count: L7 = 132 HP/2 slots vs. two L3 = 68 HP/2 slots. Tech tree text, manual, and costs updated; old saves rehydrate components by id so they pick this up safely.3. Movement points — they were shown, but labeled only "Speed". The designer now shows an explicit "Movement Points: X/turn" line.4. Design ...