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/web/routes.py

@@ -23,6 +23,7 @@ from fastapi.responses import HTMLResponse
 from fastapi.templating import Jinja2Templates
 
 from .. import __version__
+from .. import errors as _errors
 from ..auth import rotate_api_key
 from ..payload_view import prezentare_din_payload
 from ..web.csrf import get_csrf_token, verify_csrf
@@ -33,6 +34,7 @@ from .labels import (
     eticheta_worker,
     format_data_rar,
     motiv_uman,
+    parse_erori,
 )
 from ..web.session import require_login
 from ..api.v1.import_router import (
@@ -71,6 +73,8 @@ _CANONICAL_FIELDS = [(k, v[0]) for k, v in _CANONICAL_SYNONYMS.items()]
 
 router = APIRouter(tags=["web"])
 templates = Jinja2Templates(directory=str(Path(__file__).resolve().parent / "templates"))
+# Expune parse_erori in toate template-urile (US-006, PRD 5.4)
+templates.env.globals["parse_erori"] = parse_erori
 
 _BLOCKED = ("error", "needs_data", "needs_mapping")
 
@@ -604,6 +608,7 @@ def _detaliu_ctx(request: Request, row, *, message: str | None = None,
         "rar_status_code": row["rar_status_code"],
         "rar_error": row["rar_error"],
         "motiv": motiv_uman(row["status"], row["rar_error"]),
+        "erori_3n": parse_erori(row["rar_error"]),
         "retry_count": row["retry_count"],
         "created_at": format_data_rar(row["created_at"]),
         "updated_at": format_data_rar(row["updated_at"]),
@@ -1279,13 +1284,25 @@ async def web_upload_import(
     except MultipleSheets as ms:
         return templates.TemplateResponse("_upload.html", _ctx(request, sheets=ms.sheet_names))
     except FileTooLarge as e:
-        return templates.TemplateResponse("_upload.html", _ctx(request, error=str(e)))
+        eroare_upload = _errors.eroare("IMPORT_FISIER_PREA_MARE", cauza=str(e))
+        return templates.TemplateResponse("_upload.html", _ctx(
+            request, error=str(e), eroare_upload=eroare_upload
+        ))
     except HeaderError as e:
-        return templates.TemplateResponse("_upload.html", _ctx(request, error=f"Antet neclar: {e}"))
+        eroare_upload = _errors.eroare("IMPORT_ANTET_NECLAR", cauza=f"Antet neclar: {e}")
+        return templates.TemplateResponse("_upload.html", _ctx(
+            request, error=f"Antet neclar: {e}", eroare_upload=eroare_upload
+        ))
     except UnicodeDecodeError as e:
-        return templates.TemplateResponse("_upload.html", _ctx(request, error=f"Encoding nesuportat: {e.reason}"))
+        eroare_upload = _errors.eroare("IMPORT_ENCODING", cauza=f"Encoding nesuportat: {e.reason}")
+        return templates.TemplateResponse("_upload.html", _ctx(
+            request, error=f"Encoding nesuportat: {e.reason}", eroare_upload=eroare_upload
+        ))
     except Exception as e:
-        return templates.TemplateResponse("_upload.html", _ctx(request, error=f"Fisier nerecunoscut (xlsx/csv): {type(e).__name__}"))
+        eroare_upload = _errors.eroare("IMPORT_FISIER_NERECUNOSCUT", cauza=f"Fisier nerecunoscut (xlsx/csv): {type(e).__name__}")
+        return templates.TemplateResponse("_upload.html", _ctx(
+            request, error=f"Fisier nerecunoscut (xlsx/csv): {type(e).__name__}", eroare_upload=eroare_upload
+        ))
 
     conn = get_connection()
     try:
@@ -1370,6 +1387,52 @@ async def web_save_mapare_coloane(
     account_id = require_login(request)
     acct = account_or_default(account_id)
 
+    # Detecta body JSON trimis eronat (Content-Type: application/json) → COLOANE_FORMAT_JSON
+    content_type = request.headers.get("content-type", "")
+    if "application/json" in content_type:
+        body = await request.body()
+        try:
+            json.loads(body)
+            # JSON valid dar trimis pe ruta de form — tot e format gresit pentru aceasta ruta
+        except (json.JSONDecodeError, ValueError):
+            pass
+        # Indiferent daca JSON-ul e valid sau nu, Content-Type application/json e gresit pentru ruta form
+        eroare_mapare = _errors.eroare(
+            "COLOANE_FORMAT_JSON",
+            cauza="Cererea a fost trimisa ca JSON (application/json) in loc de form data.",
+        )
+        conn = get_connection()
+        try:
+            first_row = conn.execute(
+                "SELECT raw_json FROM import_rows WHERE batch_id=? ORDER BY row_index LIMIT 1",
+                (import_id,),
+            ).fetchone()
+            columns: list[str] = []
+            if first_row:
+                try:
+                    rd = decrypt_creds(first_row["raw_json"]) or {}
+                    columns = list(rd.keys())
+                except Exception:
+                    pass
+            fuzzy: dict[str, list[dict]] = {}
+            for col in columns:
+                sugg = _fuzzy_suggest_column(col, limit=3)
+                if sugg:
+                    fuzzy[col] = sugg
+            return templates.TemplateResponse("_mapcoloane.html", _ctx(
+                request,
+                import_id=import_id,
+                columns=columns,
+                sample_rows=[],
+                fuzzy_suggestions=fuzzy,
+                canonical_fields=_CANONICAL_FIELDS,
+                format_data=None,
+                eroare_mapare=eroare_mapare,
+                error=True,
+            ))
+        finally:
+            conn.close()
+
     form = await request.form()
 
     # Colectare perechi coloana fisier → camp canonic din form