[29.0] Bug 649735: [Excise Tax] Improving Excise Duty Calculation

[v-rohangarg20]

Fixes AB#649735

Issue

The 29.0 branch did not support rate-based excise duty calculation for specific-per-unit, ad valorem, and hybrid duties. In item ledger scenarios, the tax amount could also be calculated incorrectly when the final item category changed the applicable calculation type.

Cause

The calculation flow relied on the legacy item and fixed-asset rate model and did not resolve an explicit calculation type before calculating the taxable amount. The new rate model also required migration and servicing-compatible schema changes for the 29.0 branch.

Solution

• Added the Excise Tax Rate table, list page, and Excise Calculation Type enum.
• Applied the final rate and calculation type before calculating the taxable amount for item ledger entries.
• Added migration from the existing item/fixed-asset rate table.
• Updated permissions, pages, journal lines, transaction logs, and tests.
• Preserved the servicing-branch schema by excluding main-branch-only deprecation changes.

Validation

• Cherry-picked the changes from PR #11116 onto releases/29.0.
• The three source commits applied without conflicts.

[Milica Đukić (djukicmilica)]

#11002 (comment)

[alexei-dobriansky]

Good Sense Reviewer - Round 1

Recommendation: Request Changes

What this PR does

This change adds ad valorem and hybrid excise calculation types, a rate table with item-category matching, migration from the old rate setup, journal/log fields, and calculation tests. The calculation flow applies the final rate before deciding whether taxable amount is needed, but the changed posted item-ledger path is still not covered by a posting-derived regression test.

Problem-solution fit

Fit: Strong

The described scenario is clear and the diff targets that behavior directly.

Suggestions

S1 (🔴 High): Add posted-entry excise coverage
The changed item ledger entry path now sets the taxable amount from posted value entries, but the tests still exercise a manually created journal line. Please add a test that creates the item ledger entry path, generates the excise journal line, and verifies the taxable amount and tax amount. This is a tax amount path, so the exact posting-derived flow should be covered before merge.

Risk assessment and necessity

Risk: High. This is a tax amount calculation path; a missing posted-entry regression can let a wrong taxable amount or tax amount reach the excise journal and transaction log.

Necessity: The rate-model change is needed, but the posted item-ledger flow must be proven because that is where the production taxable amount is sourced.

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