REQ_01_01: Missing 'shall' in 4 communication feature requirements

## Finding from Requirements Inspection (REQ_01_01)

The following feat_req do not use "shall" in their requirement body text, violating the requirement sentence template:

- feat_req__com__interfaces
- feat_req__com__event_type
- feat_req__com__signal
- feat_req__com__service_instance_names

**File:** docs/features/communication/docs/requirements/index.rst

## Acceptance Criteria
All requirement bodies must contain at least one "shall" statement.