Update expense VAT specification source

[Alexander Yakunin (Alexander-Ya)]

This pull request introduces several important changes to the Expense Agent application, focusing on enforcing stricter controls over the creation and modification of VAT specification records, improving data integrity, and enhancing error handling and reporting. The changes ensure that records created via the Expense Agent API are clearly distinguished and protected from modification, and that error messages during expense report posting are more informative and actionable.

Key changes include:

1. Enforcing Source-based Controls and Data Integrity

• Added logic to set the Source field to Agent when VAT specifications are created via the API, and to Manual when created through the UI. This distinction is enforced in both the API and page triggers (OnNewRecord, OnInsertRecord). [1] [2]
• Made the Source field non-editable and added system metadata classification in the Expense VAT Specification table.
• Added validation logic throughout the Expense VAT Specification table to skip certain field validations and calculations if the Source is Agent, ensuring agent-created records are handled differently from manual entries. [1] [2] [3] [4] [5] [6] [7]

2. Preventing Unauthorized Modifications

• Introduced triggers to block modifications and deletions of VAT specification records created by the Expense Agent API, with clear error messages. [1] [2]
• Updated the UpdateVATSpecification procedure to prevent overwriting or deleting agent-created VAT specification lines, enforcing immutability for API-generated records.

3. Expense VAT Specification Generation and Categorization

• Improved logic for generating VAT specification lines, ensuring that manual and agent-created lines are handled separately and that the correct Source is set during creation. [1] [2]
• Ensured that the correct category and subcategory fields are validated and set only for manual entries, not for agent-created lines. [1] [2] [3]

4. Enhanced Error Handling and User Feedback

• Improved error reporting during expense report posting by introducing more specific error messages and navigation actions when VAT reclaim status is pending, making it easier for users to resolve issues. [1] [2]
• Added a helper procedure to generate detailed ErrorInfo objects for pending VAT reclaim statuses, including navigation actions for user convenience.

5. Miscellaneous Improvements

• Ensured that string values (e.g., Expense Location) are properly truncated to fit field length constraints, preventing data errors.
• When creating expense report lines from VAT specs, now copies currency code and factor from the expense, and updates reimbursement amounts for accuracy. [1] [2]
• Adjusted rounding difference logic to handle both amount and local currency amount, improving accuracy in posting. [1] [2]

These changes collectively improve the robustness, security, and usability of the Expense Agent's VAT specification handling and expense report posting workflows.<!--
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What & why

Linked work

Fixes AB#626087

How I validated this

• I read the full diff and it contains only changes I intended.
• I built the affected app(s) locally with no new analyzer warnings.
• I ran the change in Business Central and confirmed it behaves as expected.
• I added or updated tests for the new behavior, or explained below why none are needed.

What I tested and the outcome (required — be specific: scenarios, commands, screenshots for UI changes)

Risk & compatibility

[Joshua (mynjj)]

Consider hardening the upgrade