Tech Titans Unleash Revolutionary Reaction Set Feature in Major Update!

New enhancements boost user interaction and streamline messaging, setting the stage for dynamic engagement like never before!

Commit Details:

feat: add reaction set (#190) * feat: add reaction set * fix: incorrect method call * feat: reactionsByTargetKey accepts optional type param * fix: reactionsAddsKeys and reactionRemoveKeys index by type, then target * refactor: rename tsx (transaction) to txn * fix: mergeAdd throws on missing castId * test: add unit test coverage * test: add more coverage * fix: remove duplicated imports * chore: rename model.ts to messageModel.ts to match class name * refactor: condense import statement * docs: for private methods * refactor: user prefix to postfix * chore: cleanup comments