concurrency: clean up test-to-requirement traceability

Apply the test-to-requirement traceability clean-up described in #522 to the Concurrency component (`score/concurrency/`).

Replace legacy `SCR-*` `Verifies` links with mandated `FullyVerifies` or `PartiallyVerifies` links to current `comp_req__concurrency__...` needs, together with `TestType`, `DerivationTechnique`, and self-contained `Description` metadata. Review every C++ gtest against the requirements and test behavior in both directions. Do not assign artificial test coverage to requirements that are verifiable only by inspection.

## Requirement relocation from Memory

`AtomicIndirector` and its mock interface moved from `score/memory/shared` to `score/concurrency` in July 2026. The old Memory targets are deprecated forwarding shims only.

`comp_req__memory__atomic_ops` must not be linked to the relocated AtomicIndirector tests: it claims lock-free operations on shared-memory data for inter-process communication, while AtomicIndirector is a static-dispatch seam around `std::atomic` that enables testing of atomic-dependent code.

As part of this task, determine the appropriate Concurrency requirement allocation for AtomicIndirector.

Start in score/concurrency/ and inspect every C++ gtest alongside its current requirement metadata, then compare test-to-requirement and requirement-to-test coverage in both directions. Review the relocated AtomicIndirector tests and the deprecated score/memory/shared forwarding targets, determining the appropriate Concurrency requirement without linking comp_req__memory__atomic_ops. Done means legacy SCR-* links are replaced with mandated metadata and inspection-only requirements are not given artificial coverage.

Written by the indexing model from the issue text.