CCM-22997: Shared utilities

[rhyscoxnhs]

Description

Introduces a new publishable package, @nhsdigital/nhs-notify-shared-utils, in a new
packages/ workspace. It holds generic, technical-only utilities for reuse across NHS
Notify bounded contexts.

Each module is a subpath export, so a consumer imports only what it needs and Lambda
bundles never pull in test-only code:

• ./logger — a generic pino-backed Logger. Redaction is fully opt-in: the class
  declares no redact paths of its own; each bounded context supplies its own via
  redactPaths.
• ./lambda-utils — requireEnv / MissingEnvironmentVariableError, a pure
  formatZodIssues formatter, and SQS string-attribute readers. No AWS SDK dependency.
• ./test-support — integration test helpers: deployment/naming helpers, polling
  primitives, and an override-based event-factory base. AWS client factories are split
  per service under ./test-support/{cloudwatch,sqs,s3,dynamodb,eventbridge}, so
  importing one service does not load the others' AWS SDK packages; the barrel itself is
  AWS-SDK-free.
• ./s3-json — a get-JSON-from-S3-and-optionally-validate helper.

Dependency and build contract:

• pino and the AWS SDK v3 clients are peer dependencies (AWS SDK peers optional),
  preventing duplicate copies in consumer bundles.
• CommonJS build via tsc with a split tooling/build tsconfig; files restricted to
  dist. Every module ships a README with usage.

Workspace and release wiring:

• Adds the packages/* workspace glob, aws and runtime pnpm catalogs, a
  cache-correct turbo build task, and ESLint coverage for the new package.
• Adds a tag-driven publish workflow (publish-packages.yaml) to GitHub Packages under
  @nhsdigital, triggered only by shared-utils-v* tags and decoupled from the
  Terraform module release. It fails unless the pushed tag version matches package.json
version. Least-privilege permissions (contents: read, packages: write),
  GITHUB_TOKEN auth only.
• Updates existing tsconfigs to resolve typecheck / unit test failures due to missing jest entry in types and use of deprecated baseUrl properties
• 100% unit-test coverage; lint, typecheck, tests and build are green.

Context

The app-response and client-callbacks bounded contexts independently built
near-identical technical utilities — structured logging, environment-variable
validation, AWS SDK client factories, and integration test-support helpers. Maintaining
two copies causes drift and doubled effort. This extracts the generic, technical-only
utilities into a single versioned package so bounded contexts can depend on one shared
implementation, keeping the dependency one-way (bounded context → shared) and leaving
all domain logic in its own context. Consumers adopt it on their own cadence in
follow-up work; this change only introduces the package in the host repository.

Ref: CCM-22997.

Type of changes

• Refactoring (non-breaking change)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would change existing functionality)
• Bug fix (non-breaking change which fixes an issue)

Checklist

• I am familiar with the contributing guidelines
• I have followed the code style of the project
• I have added tests to cover my changes
• I have updated the documentation accordingly
• This PR is a result of pair or mob programming

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Sensitive Information Declaration

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• I confirm that neither PII/PID nor sensitive data are included in this PR and the codebase changes.