feat(import): T1 accounts.rar_creds_enc durabil + worker fallback + gate purjare

- worker: _creds_from_account(conn, account_id) — fallback la accounts.rar_creds_enc
  cand submission n-are creds (canal web fara re-pusher, restart worker)
- run(): creds = _creds_for(claimed, settings) OR _creds_from_account(conn, account_id)
- gate purjare (Voce#5): comentariu explicit — sterge DOAR submissions.rar_creds_enc,
  NU accounts.rar_creds_enc (inofensiv pt canal web, neatins pt canal API)
- POST /v1/conturi/rar-creds: seteaza creds durabile criptate Fernet per cont
- DELETE /v1/conturi/rar-creds: revenire la modelul efemer Treapta 1
- 7 teste: fallback, restart, coada mixta, endpoint set/delete, gate purjare

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/api/v1/router.py

@@ -323,3 +323,48 @@ def create_mapare(
         return {"saved": {"cod_op_service": req.cod_op_service.strip(), "cod_prestatie": cod}, "reresolve": stats}
     finally:
         conn.close()
+
+
+class RarCredsIn(BaseModel):
+    """Creds RAR durabile per-cont (D4). Stocate criptate (Fernet) in accounts.rar_creds_enc."""
+
+    email: str = Field(..., min_length=1)
+    password: str = Field(..., min_length=1, repr=False)
+
+
+@router.post("/conturi/rar-creds")
+def set_rar_creds(
+    req: RarCredsIn,
+    account_id: int = Depends(resolve_account_id),
+) -> dict:
+    """Seteaza creds RAR durabile per-cont (D4/T1).
+
+    Criptate Fernet in accounts.rar_creds_enc. Worker-ul le foloseste ca fallback
+    cand submission-ul nu mai are creds (canal web fara re-pusher, restart worker).
+    Contul vine din cheia API.
+    """
+    acct = account_or_default(account_id)
+    enc = encrypt_creds({"email": req.email, "password": req.password})
+    conn = get_connection()
+    try:
+        conn.execute(
+            "UPDATE accounts SET rar_creds_enc=? WHERE id=?",
+            (enc, acct),
+        )
+        return {"ok": True, "account_id": acct}
+    finally:
+        conn.close()
+
+
+@router.delete("/conturi/rar-creds")
+def delete_rar_creds(
+    account_id: int = Depends(resolve_account_id),
+) -> dict:
+    """Sterge creds RAR durabile per-cont (revenire la modelul efemer Treapta 1)."""
+    acct = account_or_default(account_id)
+    conn = get_connection()
+    try:
+        conn.execute("UPDATE accounts SET rar_creds_enc=NULL WHERE id=?", (acct,))
+        return {"ok": True, "account_id": acct}
+    finally:
+        conn.close()