feat(errors): erori pe 3 niveluri (problema+cauza+fix) pe API si UI (PRD 5.4)

Catalog central pur app/errors.py ca sursa unica cod->{problema,fix},
consumat de API+UI+worker. Aditiv (field/message pastrate la octet) +
rar_error stocat superset. Scope: fluxul de declarare; login/signup/CSRF
neatinse. labels.parse_erori degradeaza gratios; UI progresiv AA light+dark.
631 teste.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/api/v1/router.py

@@ -22,6 +22,7 @@ from pydantic import BaseModel, Field
 from ...auth import resolve_account_id
 from ...crypto import encrypt_creds
 from ...db import get_connection
+from ...errors import eroare as err_eroare
 from ...idempotency import build_key, canonicalize_row
 from ...mapping import (
     account_or_default,
@@ -133,12 +134,17 @@ def valideaza_prezentari(
         for i, prez in enumerate(req.prezentari):
             content = prez.model_dump()
             res = classify_prezentare(content, mapping, mapping_meta)
+            # US-003: imbogatim fiecare element nemapat cu 3 niveluri COD_NEMAPAT
+            nemapate = [
+                {**u, **err_eroare("COD_NEMAPAT", cauza=f"cod {u.get('cod_op_service')} fara mapare RAR")}
+                for u in res["unmapped"]
+            ]
             results.append(ValidareResult(
                 index=i,
                 valid=(res["status"] == "queued"),
                 status_estimat=res["status"],
                 erori=res["errors"],
-                nemapate=res["unmapped"],
+                nemapate=nemapate,
                 prestatii_rezolvate=res["resolved"],
             ))
     finally: