feat: send calendar report emails through SNS

[hughgrigg]

Add optional RollupSummaries.reportNotifications configuration for plain-text SNS digests after selected calendar reports close. The report job writes an S3 completion manifest after all calculations succeed. An S3 event invokes a Lambda that reads the current and previous reports, formats their stored comparison, and publishes to a supplied or construct-owned topic. The construct can create email subscriptions and gives the publisher an SQS dead-letter queue. SNS, S3, Lambda and SQS charge for requests, execution, data or storage and add no hourly capacity charge. The focused notification suite passes 26 tests with 95.38% branch coverage. pnpm check passes every non-test check and then fails in 81 unrelated Yulin simulation tests that cannot see their simulated S3 buckets.

• Conventional commit message, used as the title

• Conventional branch name, like feat/concise-description

• Full check with pnpm run check passed

• Rebased off latest main

• User-facing behaviour is documented in docs/

[hughgrigg]

@coderabbitai full review

[coderabbitai]

⚠️ Action not completed

Pull request is closed.