This update adds missing tax exemption reasons to the electronic invoicing system to ensure full compliance with Peppol standards. The change enables businesses to properly document all types of tax exemptions when creating electronic invoices, improving accuracy and regulatory compliance in cross-border transactions.

Some tax exemption reasons were missing,
This commit ensures having all the tax exemption reasons introduced by Peppol

task-6048561

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The system now allows companies to register PEPPOL numbers from any country, not just those on a predefined list. This removes geographic restrictions and makes the invoicing system more flexible for businesses operating internationally or with international partners.

Before this commit, only numbers on the peppol list were able to be registered. Now is possible to add numbers from other countries.

Task-6033336

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This improvement makes product matching during imports more accurate and flexible. Products are now matched regardless of uppercase/lowercase differences (e.g., "Network Cable" matches "network cable"), and the system uses intelligent similarity matching instead of simple substring search to avoid incorrectly pairing unrelated products. This results in fewer import errors and better data accuracy when bringing in product information.

Before this commit:

- Product retrieval during import relied on exact name match and substring (ilike) search.
- Exact name search was case sensitive, so values like `Network Cable` would not match `Network cable`.
- Substring matching could return unrelated products (e.g. `Wireless bluetooth speaker` gets matched with
  `Wireless bluetooth speaker battery`), leading to unrelated matches.

After this commit:

- Exact name search is now case insensitive, allowing matches such as `Network Cable` and `network cable`.
- Substring based matching has been replaced with a similarity ratio (90%) to reduce false positives and improve matching reliability against customer database product names.

Technical:

- Replaced `=` with `=ilike` in the exact name search domain to make the lookup case insensitive.
- Similarity ratio is computed using Python's `difflib.SequenceMatcher` on product names, with a minimum threshold of 90% to qualify as a match.
- Added system parameter for configurable product name similarity threshold.

task-5951469

This fix corrects an overly strict warning that appeared when generating payslips for employees whose contracts partially overlap with the payslip period. Previously, the system required the contract to fully contain the payslip dates; now it correctly allows payslip generation as long as there is at least one day of overlap between the contract and payslip period. This resolves false warnings that prevented legitimate payslip processing.