campaign package

Package campaign is a near-verbatim copy of the real gems6/campaign realm, redeployed here under the test address so this whole reveal-delay + gemsartfab prototype is self-contained and testable without touching the live gems6 deployment or needing the vesting wallet's own key. Logic is unchanged from the original -- see that package's own doc comments for the full design rationale (why a dedicated prunable realm instead of a Merkle root, the stacking rule in grantOne, etc.).