[Osuochasam]

SummaryThis PR resolves event processing vulnerabilities across the SDK by introducing a deduplication primitive (ProcessedSet), a managed polling stream driver (EventStream), and ledger-reorg rewind capabilities. It guarantees idempotent event processing and eliminates per-repository polling loop divergence.Key Changes1. Deduplication Primitive (src/events/processed-set.ts)Introduced the ProcessedSet interface and an InMemoryProcessedSet implementation.Uses an $O(1)$ FIFO-evicting strategy with a default capacity of 10,000 entries to prevent memory leaks while blocking duplicate event execution.2. Stream Driver & Reorg Handling (src/events/stream.ts)Created the EventStream class to own polling loops, pagination, and backoff logic.Features exponential back-off with 10% random jitter and native AbortSignal support.Detects unresolvable cursors during ledger reorganizations and rewinds to the last known-good state.Guarantees zero active timer handles when stop() is invoked.3. Cursor & Deduplication Integration (src/events/cursor.ts)Added optional StreamEvent.id field and integrated ProcessedSet checks into EventCursor.process().Preserves strict no-skip ordering: execution proceeds only if unprocessed, followed by store.set() and then processedSet.add().Added a reset() method to support cursor rewinds during reorgs.4. Public Exports & Test Coverage (src/events/index.ts, src/tests/events.test.ts)Re-exported ProcessedSet, InMemoryProcessedSet, and EventStream.Added 16 new unit tests across 5 describe blocks validating deduplication, timer cleanup, throw safety, and reorg rewinds.Quality GatesUnit Tests: npm test $\rightarrow$ 214/214 passed (100%)TypeScript: npm run typecheck $\rightarrow$ 0 errorsLinter: npm run lint $\rightarrow$ 0 errorsBuild: npm run build $\rightarrow$ Clean CJS & ESM outputs

Closes #87