refactor(commons): extract InvokeStore fallback into InvocationScoped

[dreamorosi]

Summary

Extracts repeated invocation-scoping behavior from seven logger, metrics, and batch stores into a tested commons primitive. This removes inconsistent fallback and error behavior while leaving each store responsible only for its domain logic.

Changes

• Replace 36 repeated accessor branches across seven stores. Previously, only LogInvocationStore.setLogLevel guarded on hasContext(), while BatchProcessingStore asserted InvokeStore in only 2 of 14 accessors, producing inconsistent TypeError and Error failures.
• Add the internal InvocationScoped<T> commons subpath export at ./utils/invocation-scoped, with direct coverage for the flag-off, missing-global, inactive-context, and scoped modes. Scoped and shared slots use Box<T> so explicit undefined shadows the shared value while an unset slot falls back.
• Migrate the logger, metrics, and batch stores to invocation-scoped cells. Writes outside an active invocation use shared storage, every accessor reports InvokeStore is not available when required, and MetricsStore.clearMetrics clears its timestamp consistently in both modes.
• Move @aws/lambda-invoke-store to devDependencies in logger, metrics, and batch because their sources no longer import it; commons retains the runtime augmentation while tests continue using it directly.
• Notes for reviewers:
  • Private pass-through getters remain in the stores.
  • Box<T> deliberately distinguishes an explicit undefined value from an unset slot.
  • Commons retains the bare import '@aws/lambda-invoke-store' for runtime augmentation.
  • Batch errors pushed before prepare() now persist under concurrency; this is deliberate unification and is not externally observable.
  • LogInvocationStore continues relying on the existing configureBuffer() precondition.
  • Copy semantics remain unchanged and out of scope.
  • Tracer is deliberately untouched because its fallback is the X-Ray SDK context rather than an instance field.
• Verification: 100% unit coverage in commons (238), logger (238), metrics (164), and batch (128); tracer has 113 passing tests; lint:ci is clean.

Issue number: closes #5554

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