docs: correct replayFromLedger idempotency claims in JSDoc and swagge…

[CHKM001]

PR #808 [Docs] Correct replayFromLedger idempotency claims in JSDoc & swagger summary

Closes #808

Summary

The replayFromLedger JSDoc falsely claimed that worker deduplication guarantees idempotent replay. This is only true for StreamEvent rows (via the @@unique([transactionHash, eventType]) constraint), but not for stream state mutations like Stream.withdrawnAmount in handleTokensWithdrawn.

Changes

backend/src/services/indexerService.ts

• Updated the replayFromLedger JSDoc to:
  • Clearly state that the @@unique([transactionHash, eventType]) constraint guarantees no duplicate StreamEvent rows on replay
  • Add a CAVEAT noting that stream state mutations (e.g., Stream.withdrawnAmount in handleTokensWithdrawn at soroban-event-worker.ts:635) are not idempotent — they execute unconditionally on every replay
  • Cross-reference issue [Docs] replayFromLedger JSDoc falsely claims worker dedup guarantees idempotent replay #808 for the withdrawnAmount idempotency fix

backend/src/routes/v1/admin.routes.ts

• Changed the /v1/admin/indexer/replay swagger summary from (idempotent) to (StreamEvent rows deduplicated; stream mutations not idempotent — see indexerService.ts JSDoc)

Non-idempotent mutations

Handler	Mutation	Idempotent?
handleTokensWithdrawn	Stream.withdrawnAmount increment	No — double-counts on replay
handleStreamToppedUp	depositedAmount / endTime update	No
handleStreamCancelled	isActive / withdrawnAmount update	No
handleStreamCompleted	isActive update	No
handleStreamPaused	isPaused update	No
handleStreamResumed	totalPausedDuration update	No
handleStreamCreated	stream.upsert	Yes
handleFeeCollected	streamEvent.upsert only	Yes
handleFeeConfigUpdated	streamEvent.upsert only	Yes
handleAdminTransferred	streamEvent.upsert only	Yes

Files touched

• backend/src/services/indexerService.ts
• backend/src/routes/v1/admin.routes.ts

Out of scope

• Fixing the non-idempotent handleTokensWithdrawn logic itself (tracked in [Docs] replayFromLedger JSDoc falsely claims worker dedup guarantees idempotent replay #808)
• Writing a full services README

Closes #808