Support filtering specification items by status

[kaklakariada]

OpenFastTrace currently supports filtering imported specification items by artifact type and tags, but not by item status.

Use case:
Projects can mark reverse-engineered or not-yet-reviewed items with the conventional field Status: draft. Those items should be excluded from trace verification until promoted, without having to duplicate the state in Tags: draft or require an unrelated Tags: active marker.

Requested behavior:

• Add a trace/import filter for status values, for example include only non-draft items or exclude Status: draft.
• Keep the existing tag filtering behavior unchanged.
• Document how status filtering interacts with items that do not declare a status.

Workaround:

• Filter by status active
• Add Tags: draft to items in status draft
• Replace tag draft with active once an item is no long a draft.