ts_client: Create SW component requirements and establish traceability

> [!IMPORTANT]
> Link the implementing PR to this issue by including `Closes #75` in the PR description or commit message.

### What

Write the component requirements document for `score/ts_client`.

`score/ts_client` has production code (gPTP IPC publisher/receiver) and active
development (PR #54 replacing mmap with SharedMemoryFactory) but no component
requirements. Requirements shall be authored as `comp_req` sphinx-needs directives
at `score/ts_client/docs/requirements/ts_client_requirements.rst`, traced to
feature requirements via `:satisfies: feat_req__time__`, and back-linked to
code via `// # req-Id:` comments.

### Acceptance Criteria

- [ ] `score/ts_client/docs/requirements/ts_client_requirements.rst` created and indexed
- [ ] All significant observable behaviours covered as `comp_req` nodes (connect/disconnect, publish, receive, error paths)
- [ ] Every `comp_req` has a `:satisfies:` link to a valid `feat_req`
- [ ] Every `comp_req` traced to code via `// # req-Id:`

### References

- [S-CORE Requirements Engineering](https://eclipse-score.github.io/process_description/main/process_areas/requirements_engineering/)