**Steps to reproduce:**
* Install the **l10n_es_edi_sii** module.
* Create a **Portuguese customer**.
* Go to **Settings** and enable **EU Intra-community Distance Selling**, then refresh the tax mapping.
* Create a customer invoice with a **"No Sujeto por reglas de localización"** tax (e.g. **23.0% PT VAT**).
* Go to **Accounting → Reporting → Tax Report → OSS Sales**.
* Export the **VAT Record Books (XLSX)** file and open it.

**Observed behavior:**
* The "Clave de Operación" column shows "01" for lines with no_sujeto_loc taxes instead of "17".
* The SII JSON for the same invoice correctly shows "ClaveRegimenEspecialOTrascendencia": "17".

**Cause:**
* In `_l10n_es_libros_get_common_line_vals()`, `operation_code` was computed manually as `'02' if exempt_reason else '01'`, which only handled the E2 exempt case and defaulted everything else to "01".
* This missed OSS/no_sujeto_loc taxes (e.g. FR VAT, PT VAT) that should produce "17" per the Spanish VAT regime code table.

**Fix:**
* Extract operation code computation into a new dedicated method `_l10n_es_libros_get_operation_code()`.
* For customer invoices, delegate to the existing `_l10n_es_get_regime_code()` method already used by SII, which correctly returns "17" for OSS-tagged taxes, "02" for E2 exempt, and "01" otherwise.
* For vendor bills, mirror the SII logic by checking whether the invoice taxes include tags from `mod_303_casilla_10_balance` or `mod_303_casilla_11_balance` (intra-community indicators), returning "09" if so and "01" otherwise.

opw-6197141,6216485

Forward-Port-Of: odoo/enterprise#117236