Add DynamoStreamHandler (v8.1.0)

[mckalexee]

Summary

Adds a sixth handler type, DynamoStreamHandler, for processing DynamoDB streams, and sets up release infrastructure (CHANGELOG + GitHub Release step). Releases v8.1.0.

DynamoStreamHandler

• New handler factory in handlers/dynamo-stream-handler.ts. Records pass through raw (images stay in DynamoDB AttributeValue form — no unmarshalling, no new dependency). Return a retry list to report failed records; the wrapper maps each to its SequenceNumber for partial batch response. A thrown error fails the whole batch.
• Stream retries are checkpoint-based (Lambda rewinds to the earliest failure), so handlers must be idempotent — documented in the factory and README.
• ServiceDynamoStreamFunction wires a DynamoEventSource with startingPosition (default TRIM_HORIZON), batchSize, maxBatchingWindow, retryAttempts, bisectBatchOnError, parallelizationFactor, maxRecordAge, and reportBatchItemFailures: true.
• The source table is referenced by name via a new tables map on LambdaService, mirroring the existing eventBuses pattern. Handler authors write only a string tableName; the ITable is supplied where the service is created.

Out of scope (deliberately): image unmarshalling, onFailure DLQ destination, and filterCriteria.

Release infrastructure

• New CHANGELOG.md (Keep a Changelog format), seeded with 8.1.0 and 8.0.1.
• publish.yml now creates a GitHub Release from the matching CHANGELOG section (contents: write), and bumps actions/checkout / actions/setup-node v4 → v6.
• New "Releasing" section in CLAUDE.md documenting the cut-a-release process.

Tests

• Unit tests for the handler wrapper (success / void / partial {retry} mapping / throw-fails-batch).
• Extract test asserts the new dynamoStream bucket.
• Infra test asserts the EventSourceMapping has StartingPosition: TRIM_HORIZON and FunctionResponseTypes: [ReportBatchItemFailures]; snapshot updated for the one new Lambda.
• npm run build clean, all 39 tests pass.

Releasing after merge

Tag the merge commit: git tag v8.1.0 && git push origin v8.1.0 → publishes to npm (latest) and creates the GitHub Release.

[github-actions]

Test Results

 1 files  ±0  11 suites  +2   16s ⏱️ +6s
38 tests +5  38 ✅ +5  0 💤 ±0  0 ❌ ±0 
39 runs  +5  39 ✅ +5  0 💤 ±0  0 ❌ ±0 

Results for commit e4e9bf2. ± Comparison against base commit 770f863.

[github-actions]

Test Results

 1 files  ±0  11 suites  +2   19s ⏱️ +9s
40 tests +7  40 ✅ +7  0 💤 ±0  0 ❌ ±0 
41 runs  +7  41 ✅ +7  0 💤 ±0  0 ❌ ±0 

Results for commit 7513b13. ± Comparison against base commit 770f863.

♻️ This comment has been updated with latest results.

[codecov]

Codecov Report

❌ Patch coverage is 89.28571% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.77%. Comparing base (770f863) to head (7513b13).

Files with missing lines	Patch %	Lines
constructs/service-dynamo-stream-function.ts	77.77%	2 Missing and 2 partials ⚠️
constructs/lambda-service.ts	80.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #63      +/-   ##
==========================================
+ Coverage   83.14%   83.77%   +0.62%     
==========================================
  Files          24       26       +2     
  Lines         623      678      +55     
  Branches      148      161      +13     
==========================================
+ Hits          518      568      +50     
- Misses        103      106       +3     
- Partials        2        4       +2     

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