Mem-Client: MDS Components Use export const

MDS component exports should use `export const` component declarations.

Rationale:
- Consistent component declaration style simplifies scanning and refactors.

Scope:
- PR review policy for new MDS component source files under `domains/frontend/mem-client/src/mds/components/**`.
- Excludes `*.stories.tsx`, `*.style.tsx`, `*.types.ts`, and `index.ts`.

Trigger:
- A PR introduces new exported React component declarations in scope.

Approval checks:
1) New exported React components use `export const` declarations.
2) New `export function` component declarations are not introduced in scope.

Evidence:
- Diff of component file exports matches declaration convention.

Decision:
- Return NOT APPROVED when trigger is met and declaration convention is violated.