Point of Sale now keeps the product's normal tax when a selected fiscal position does not define a specific tax mapping. This prevents sales from being recorded without tax in that scenario, helping ensure more accurate checkout totals and tax reporting.

**Description of the issue/feature this PR addresses:**

If a fiscal position is set in the point of sale and a product tax
isn't mapped in it no tax will be applied for that product.

**Current behavior before PR:**

Taxes aren't applied in such case

**Desired behavior after PR is merged:**

Taxes default to the product defined ones if no map is set in the fp

cc @Tecnativa

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This update fixes several issues in the website slides and learning content area, including broken statistics, PDF display problems, and unreliable like/dislike actions. It also improves access handling so users only see upload and tagging options when they have the right permissions.

Purpose of this merge it to merge various fixes and small improvements
related to slides module. As an update of this module is pending fixing
it before is quite helpful.

This merge is linked to task ID 1933820 and PR #30553.

This update brings forward a set of fixes that improve day-to-day reliability in accounting, inventory, website sales, and project views. It prevents incorrect accounting references and tax totals, preserves manufacturing consumption data, restores missing messages/options, and improves compatibility on small screens and different browsers.