Fix weight-based shipping rate breakpoints evaluation

[Huncsuga]

Description

• This PR fixes an issue where weight-based shipping rates ignore or inconsistently apply pricing breakpoints due to mismatched weight units during comparison.

• When a Shipping Method is configured with Charge By: Weight, the cart’s total weight and the pricing break min_quantity values are not normalized to the same unit. As a result, defined Shipping Breakdowns (tiers) are skipped and the base price is often returned regardless of the actual cart weight.

• This change ensures that both values are compared using a consistent weight unit, allowing pricing breakpoints to be evaluated correctly.

Related Issue

Fixes #2381

Type

Bug fix

What was changed

• Normalized weight unit handling when evaluating shipping rate pricing breaks

• Removed incorrect scaling (×100) applied when saving weight-based pricing break values

• Ensured pricing break thresholds are stored and evaluated using the same unit as cart weight calculations

Expected Outcome

• Weight-based shipping tiers are applied correctly as cart weight increases

• Pricing breaks behave consistently regardless of the product’s configured weight unit (g / kg / lbs)

How to test

1. Create a Shipping Method with Charge By: Weight
2. Assign the Shipping Method to a Zone
3. Create a Shipping Rate with multiple weight-based pricing breaks (e.g. 5, 10)
4. Create two product variants:
   • Variant A: weight = 2 kg
   • Variant B: weight = 1500 g
5. Add the following items to the cart:
   • 1 × Variant A (2 kg)
   • 3 × Variant B (3 × 1500 g = 4.5 kg)
6. Verify that the shipping rate correctly evaluates the total cart weight (6.5 kg)
7. Confirm that the appropriate pricing tier is applied based on the combined weight

[Copilot]

Pull request overview

This PR fixes a bug where weight-based shipping rate breakpoints were evaluated incorrectly due to inconsistent weight unit handling. The fix ensures cart weights and pricing tier thresholds are normalized to kilograms before comparison, allowing weight-based shipping tiers to apply correctly.

Key Changes:

• Normalized all weight calculations to kilograms using the Converter facade
• Removed incorrect scaling factor (×100) when saving and loading weight-based pricing breakpoints
• Added UI helper text and suffix to clarify that weight thresholds should be entered in kg

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
packages/table-rate-shipping/src/Drivers/ShippingMethods/ShipBy.php	Converts product weights to kg before calculating total cart weight
packages/table-rate-shipping/src/Filament/Resources/ShippingZoneResource/Pages/ManageShippingRates.php	Removes ×100 scaling for weight values and adds kg suffix/helper text to form field
packages/table-rate-shipping/resources/lang/en/relationmanagers.php	Adds English helper text indicating weight should be entered in kg
packages/table-rate-shipping/resources/lang/ro/relationmanagers.php	Adds Romanian helper text indicating weight should be entered in kg
packages/table-rate-shipping/resources/lang/hu/relationmanagers.php	Adds Hungarian helper text indicating weight should be entered in kg

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