feat: Serverless Framework v4 support + plugin hardening (offline s3/sqs/kinesis/dynamodb-streams)

[silouone]

What & why

Serverless Framework v4 removed @serverless/utils/log and serverless.cli.log. Our four
serverless-offline-* plugins require that module at load time, so they crash on every sls
command under v4 (sls package, sls offline, …). This PR migrates all four to the logger that
the framework injects as the plugin constructor's 3rd argument ({log}) — which has existed
since serverless v3.0, so the change is backward compatible with v3.

While we were in here owning this code, we also re-implemented the worthwhile ideas from several
long-open community PRs as our own, tested code, and fixed a batch of latent bugs the migration
surfaced.

Supersedes the partial v4 PR #264 (s3+sqs only): this covers all four plugins, keeps peers
wide (no forced v14 cutover), and adds the unit tests + correctness fixes that one was missing.
See docs/serverless-v4-migration-review.md and docs/open-pr-triage.md for the full analysis.

Changes per package

All four — remove the dead @serverless/utils/log require; take {log} from the 3rd ctor arg via a
new src/log.js shim (full level set, console fallback); thread it into the emulator; replace
serverless.cli.log → this.log.notice. Minor version bump; peer kept ^10.0.2 || >=11.

• serverless-offline-s3 (7.1.0) — fix log.warn→log.warning; delete dead _create/_s3Event
  methods and the now-orphaned s3-event-definition.js.
• serverless-offline-sqs (8.1.0) — fix this.region→this.options.region so events carry the
  right awsRegion (fix: remove undefined reference to this.region #166, thanks @zlalvani); unique deleteMessageBatch entry Ids within a batch
  (fix: SQS Delete Batch ID's should be distinct, which MessageID is not guaranteed to be #253, thanks @flipscholtz); custom.serverless-offline-sqs.queueName override (chore(serverless-offline-sqs): allow passing queueName from config #211, thanks
  @mfamilia).
• serverless-offline-kinesis (7.1.0) — awsRegion fix (fix: remove undefined reference to this.region #166); replace the infinite silent
  handler retry with a bounded, logged retry (default maximumRetryAttempts: 10, mirrors
  dynamodb-streams) (feat(offline-dynamodb-streams): add retries option #100, thanks @dolsem); await lambda.create(...) (Fix module import bug #249, thanks @gabsong);
  fix kinesis-event-definition omit list (tableName→streamName copy-paste bug); now logs handler errors.
• serverless-offline-dynamodb-streams (7.1.0) — awsRegion fix (fix: remove undefined reference to this.region #166); clear
  Table <name> does not have streams enabled error (feat(offline-dynamodb-streams): table does not have streams error #98, thanks @dolsem); rename the
  copy-pasted KinesisEvent class to DynamodbStreamsEvent; now logs handler errors.

Compatibility

• Works on serverless v3 and v4 (the {log} 3rd arg exists in both; console fallback if absent).
• Peer ranges kept wide (serverless-offline: ^10.0.2 || >=11) — services can migrate one at a time.
• Minor version bumps (behavior-preserving + additive). No new runtime dependencies.

Testing

• ✅ npm run eslint (lint + Prettier) clean across the repo.
• ✅ 71 new docker-free AVA unit tests — the offline plugins previously had zero unit tests.
  Covers the log shim, the event mappers (with awsRegion regression guards for fix: remove undefined reference to this.region #166), the
  delete-batch Id uniqueness (fix: SQS Delete Batch ID's should be distinct, which MessageID is not guaranteed to be #253), the non-mutating queueName override incl. arn-bearing shapes
  (chore(serverless-offline-sqs): allow passing queueName from config #211), the kinesis omit-fix (discriminating test), and source-level call-site guards.
• ⚠️ Not run here (documented, follow-up): the Docker integration suite
  (tests/serverless-plugins-integration, needs minio/elasticmq/kinesalite/dynamodb-local) and v4
  end-to-end (sls package/offline under serverless@4, needs SERVERLESS_ACCESS_KEY). The
  recommended CI v4 matrix is described in docs/testing-and-ci.md.

Tooling added

Repo docs under docs/ (architecture, conventions, testing-and-ci, publishing-and-versioning, the
review + triage, and per-task plans), plus a serverless-plugin-dev skill and a
serverless-plugin-author agent under .claude/ to help future work on these plugins.

Credits

Re-implements ideas from community PRs #166 (@zlalvani), #253 (@flipscholtz), #211
(@mfamilia), #98 & #100 (@dolsem), #249 (@gabsong) — thank you. 🙏

Follow-ups (not in this PR)

• CI v4 build matrix (serverless 3 and 4).
• Adds creation of dlq from resources #183 DLQ autocreate from RedrivePolicy and start non-SQS lambdas, default to localhost #168 host/start — deferred until validated
  against the Docker + v4 integration lane (see docs/plans/07-deferred-and-closed-prs.md).
• Publish (canary → stable via lerna), then bump consuming services (CLXP-103).

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