Story K: CLI updates (cmd_spec, cmd_project) for vBRIEF model

[MScottAdams]

Parent

Part of #309 (RFC: vBRIEF-centric document model)

Tier

Tier 4 -- CLI and tests (depends on all Tier 1-3 stories)

Scope

Update the Python CLI (run) to target the new vBRIEF-centric structure:

cmd_spec:

• Generate scope vBRIEFs into vbrief/proposed/ instead of vbrief/specification.vbrief.json
• Use YYYY-MM-DD-descriptive-slug.vbrief.json filename convention
• Include origin provenance in references if applicable

cmd_project:

• Generate vbrief/PROJECT-DEFINITION.vbrief.json instead of PROJECT.md
• Use narratives for project identity, items as scope registry
• Fold project config into PROJECT-DEFINITION narratives

General:

• Update any references to old file paths
• Update help text and user-facing messages

Acceptance Criteria

• cmd_spec outputs to vbrief/proposed/ with correct filename convention
• cmd_project outputs PROJECT-DEFINITION.vbrief.json with correct schema
• No references to old SPECIFICATION.md/PROJECT.md as output targets
• CLI help text reflects new structure

[MScottAdams]

Closed by squash merge of PR #355 into phase2/vbrief-cutover. cmd_spec outputs scope vBRIEFs to vbrief/proposed/, cmd_project outputs PROJECT-DEFINITION.vbrief.json.