**Steps to reproduce:**
- Install the `l10n_gt_edi` module and switch to a `GT Company`.
- Create a new vendor bill with:
  - Vendor: GT Company
  - GT Document Type: `FESP`
  - Add taxes `VAT Withholding 12%` and `ISR Withholding 5%` in Invoice lines.
- `Confirm` the bill and `Send to SAT`.
- From the gear icon, click `Download` > `PDF`.

**Error1:**
`KeyError: 'gran_total'`

**Error2:**
`KeyError: 'retencion_grand_total'`

**Root Cause:**
In commit [1], the code at [2] missed calling `_l10n_gt_edi_add_base_values()` 
before `_l10n_gt_edi_add_withholding_values()`. However, 
`_l10n_gt_edi_add_withholding_values()` uses the `gran_total` value, which is 
initialized by `_l10n_gt_edi_add_base_values()`, resulting in a `KeyError`.

Additionally, the report template at [3] references `retencion_grand_total` 
instead of the correct key `retencion_gran_total`, causing another `KeyError`.

**Fix:**
This commit prevents errors and ensures users can successfully download 
the PDF by applying a fix similar to [4],

[1]:
https://github.com/odoo/enterprise/commit/44afd19e4ed0827e343af0e584c81e579935c9e8

[2]:
https://github.com/odoo/enterprise/blob/9846b337cfe1876017c7c2ce3041569d7a2ac03f/l10n_gt_edi/models/account_move.py#L305-L328

[3]:
https://github.com/odoo/enterprise/blob/9846b337cfe1876017c7c2ce3041569d7a2ac03f/l10n_gt_edi/views/report_invoice.xml#L72

[4]:
https://github.com/odoo/enterprise/blob/9846b337cfe1876017c7c2ce3041569d7a2ac03f/l10n_gt_edi/models/account_move.py#L790-L800

opw-6323049

Forward-Port-Of: odoo/enterprise#122030

When generating an offer from the recruitment application and signing it, the applicant's email address is incorrectly displayed.

### **Steps to Reproduce:**
1) Install sign, recruitment, hr_contract_salary
2) Create an new application and add basic detail like name and email as
   (path and `path@test.com`)
3) Generate offer and sign with all the required signer(applicant and Marc Demo). 
4) Open the application form view and open the certificate.

### **Observed Behavior:**
Email is not set correctly in the generated certificate (appearing as `john@example.com`).

### **Expected Behavior:**
The email of the applicant should be correctly set(e.g as `path@test.com`)

### **Root Cause:**
When the applicant signs the document, their email is explicitly set to `False` at [1]. This is done because the applicant is not linked to any user yet. Later, when generating the certificate, the system attempts to display the user's partner email at [2], which is `False`, causing the default fallback value (`john@example.com`) to be printed.

[1]- https://github.com/odoo/enterprise/blob/49226f4109c7d7bb48340949951e70f4245d0e5b/hr_contract_salary/controllers/main.py#L53-L54

[2]- https://github.com/odoo/enterprise/blob/49226f4109c7d7bb48340949951e70f4245d0e5b/sign/report/sign_log_reports.xml#L59

### **Fix:**
Use `signer_email` instead of the partner's email to ensure the correct email is displayed on the certificate every time.

opw-6280170

Forward-Port-Of: odoo/enterprise#120566

**Steps to reproduce:**
* Install the **l10n_gt_edi** module.
* Configure a Guatemalan company with valid Infile credentials in the settings.
* Create a product or customer with special characters (e.g. `ñ`, `á`, `é`) in their name.
* Create a customer invoice containing this product/customer.
* Confirm the invoice to trigger the EDI send to the SAT (Infile).

**Observed behavior:**
* Infile intermittently rejects the invoice due to validation errors, or accepts it but the resulting certified XML has truncated or malformed text exactly where the special characters were located.

**Cause:**
* Odoo uses the `requests.post()` library to send the XML payload to Infile. By default, `requests` encodes string payloads using `latin-1` unless told otherwise.
* Because the request was missing the explicit `Content-Type: application/xml` header and the XML string was not explicitly encoded to `utf-8` before sending, Infile parsed the payload using an incorrect encoding. This caused it to drop or misinterpret special characters, leading to validation failures or corrupted XML content.

**Fix:**
* Explicitly include the `'Content-Type': 'application/xml'` header in the request to Infile.
* Explicitly encode the `xml_data` payload to `utf-8` (`xml_data.encode('utf-8')`) before passing it to `requests.post()` to guarantee the correct encoding is sent over the wire.

opw-6315654

Forward-Port-Of: odoo/enterprise#121729