Deprecation mechanism for metamodel yaml

### What

Add support for `deprecated_options` and `deprecated_links` in the metamodel.
These are **not validated** (no regex, no type checking).
They only emit **INFO-level messages** when a need still uses them, so they don't break builds
but alert users to migrate.

Example YAML syntax:

```yaml
feat_req:
title: Feature Requirement
mandatory_options:
status: ^(valid|invalid)$
optional_links:
derived_from: stkh_req
belongs_to: feat
deprecated_links:
satisfies: use derived_from instead
```

### Acceptance Criteria (DoD)

tbd

### How

tbd