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/worker/__main__.py

@@ -34,6 +34,7 @@ from datetime import datetime, timedelta, timezone
 
 import httpx
 
+from .. import errors
 from ..config import Settings, get_settings, load_test_credentials
 from ..crypto import decrypt_creds
 from ..db import get_connection, init_db, write_heartbeat
@@ -200,7 +201,14 @@ def process_one(conn, settings: Settings, rar: RarClient, token: str, claimed: d
         return "sent"
     except RarError as exc:
         if exc.status_code == 400:
-            detail = json.dumps(exc.field_errors, ensure_ascii=False) if exc.field_errors else str(exc)
+            if exc.field_errors:
+                enriched = [
+                    errors.eroare("RAR_VALIDARE", field=fe.get("field"), cauza=fe.get("message"))
+                    for fe in exc.field_errors
+                ]
+            else:
+                enriched = [errors.eroare("RAR_VALIDARE", cauza=str(exc))]
+            detail = json.dumps(enriched, ensure_ascii=False)
             mark(conn, sid, "needs_data", rar_status_code=400, rar_error=detail)
             print(f"[worker] submission {sid} -> needs_data: {detail}", flush=True)
             return "needs_data"
@@ -406,7 +414,8 @@ def run() -> int:
                 token = sessions.get_token(conn, account_id, creds)
             except RarAuthError as exc:
                 # Creds gresite (login 401): NU se face retry (plan, failure registry).
-                mark(conn, sid, "error", rar_status_code=401, rar_error="credentiale RAR invalide")
+                mark(conn, sid, "error", rar_status_code=401,
+                     rar_error=json.dumps(errors.eroare("RAR_CREDS_INVALIDE", cauza="credentiale RAR invalide"), ensure_ascii=False))
                 print(f"[worker] submission {sid} (cont {account_id}) -> error: {exc}", flush=True)
                 continue