[SrMessiSOL]

Summary

• reduce Trade Network discount from 300 to 100 bps per level
• reduce Defense Coordination discount from 400 to 150 bps per level
• cap level-25 discounts at 25% for metal/crystal/ANTIMATTER and 37.5% for deuterium
• add a regression test for maximum-level sink preservation

Verification

• cargo test --lib --manifest-path programs/game-state/Cargo.toml
• 40 tests passed

Compatibility

• no account layout changes
• existing alliance levels and treasury balances remain valid
• requires matching frontend labels after merge