Completes Fase 0 (skeleton & decision-lock):
- reference_domain.py + data/reference_projects.json: a synthetic
"anleggskostnad" portfolio (3 fictional construction-cost projects with
cost line items) as the framework's bundled reference input. Plain typed
loader (frozen dataclasses); the JSON-Schema data-source *contract* (B5)
is deliberately deferred to Fase 2.
- backends.py: Profile (azure|local) + ChatBackend Protocol seam +
AzureFoundryBackend/LocalBackend stubs + get_backend() selector
(fail-fast on unknown profile). Empty skeleton per D2 — create_chat_client
raises NotImplementedError until live wiring in Fase 1. Return type is the
MAF BaseChatClient (the common base of FoundryChatClient/OpenAIChatClient).
Quality gate green: ruff format + check, mypy (src) clean, 12 pytest passed.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01H9FyyENxebxVThjrn9et8C
