feat(core): add Sugar#useTransform method

[devin-ai-integration]

Add Sugar#useTransform method

This PR implements the Sugar#useTransform method requested in issue #14, which allows creating a new Sugar instance connected to an existing Sugar with bidirectional transformation functions.

Features

• Bidirectional transformation: Support for async forward and backward transformation functions
• Event propagation: Proper change/blur event propagation between original and transformed Sugar instances
• Type safety: Full TypeScript support with generic type parameters
• NullableStringInput example: Implements the specific use case from issue feat(core): Sugar#useTransform #14 where empty strings can be converted to null

API

const transformedSugar = sugar.useTransform<string>({
  forward: async (value: string | null) => value ?? '',
  backward: async (value: string) => value === '' ? null : value,
});

Implementation Details

• Follows the same architectural pattern as useObject and useValidation
• Creates an independent transformed Sugar instance that synchronizes with the original
• Handles proper cleanup and event listener management
• Supports template propagation with setTemplate functionality

Testing

• Includes comprehensive test case demonstrating the NullableStringInput example
• All existing tests continue to pass
• Follows proper Sugar component attachment patterns for test reliability

Files Changed

• packages/core/src/sugar/types.ts - Added type definitions
• packages/core/src/sugar/useTransform.ts - Core implementation
• packages/core/src/sugar/index.ts - Added method to SugarInner class
• tests/core-unittest/src/useTransform-simple.spec.tsx - Test cases

Link to Devin run: https://app.devin.ai/sessions/87157fa55aed4027ac092aeb3a6a7ba7

• close feat(core): Sugar#useTransform #14

[devin-ai-integration]

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[codecov]

Codecov Report

Attention: Patch coverage is 63.63636% with 12 lines in your changes missing coverage. Please review.

Project coverage is 80.11%. Comparing base (60746d1) to head (685a5bf).
Report is 1 commits behind head on main.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
packages/core/src/sugar/useTransform.ts	61.29%	12 Missing ⚠️

@@            Coverage Diff             @@
##             main      #75      +/-   ##
==========================================
- Coverage   81.15%   80.11%   -1.05%     
==========================================
  Files           7        8       +1     
  Lines         329      362      +33     
  Branches       80       85       +5     
==========================================
+ Hits          267      290      +23     
- Misses         62       72      +10     

Files with missing lines	Coverage Δ
packages/core/src/sugar/index.ts	82.90% <100.00%> (+2.03%)	⬆️
packages/core/src/sugar/useTransform.ts	61.29% <61.29%> (ø)

[codecov]

Bundle Report

Changes will increase total bundle size by 9.45kB (10.47%) ⬆️⚠️, exceeding the configured threshold of 5%.

Bundle name	Size	Change
all-@sugarform/core	70.56kB	6.69kB (10.47%) ⬆️⚠️
cjs-@sugarform/core	14.66kB	1.36kB (10.25%) ⬆️⚠️
esm-@sugarform/core	14.51kB	1.4kB (10.7%) ⬆️⚠️

Affected Assets, Files, and Routes:

view changes for bundle: esm-@sugarform/core

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
lib.js	1.4kB	14.51kB	10.7% ⚠️

view changes for bundle: all-@sugarform/core

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
lib.cjs	1.36kB	14.66kB	10.25% ⚠️
lib.js	1.4kB	14.51kB	10.7% ⚠️
lib.cjs.map	1.17kB	13.97kB	9.11% ⚠️
lib.js.map	1.16kB	12.19kB	10.51% ⚠️
sugar/types.d.ts.map	93 bytes	2.62kB	3.69%
sugar/types.d.ts	97 bytes	2.2kB	4.61%
sugar/index.d.ts.map	90 bytes	1.79kB	5.28% ⚠️
sugar/index.d.ts	92 bytes	1.76kB	5.52% ⚠️
sugar/useTransform.d.ts.map (New)	706 bytes	706 bytes	100.0% 🚀
sugar/useTransform.d.ts (New)	521 bytes	521 bytes	100.0% 🚀

view changes for bundle: cjs-@sugarform/core

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
lib.cjs	1.36kB	14.66kB	10.25% ⚠️

[AsPulse]

これ以外の部分はヨシ!! テストの内容も問題なし。

[AsPulse]

mainブランチの変更を取りこみましょう。templateの形が変わっています。
これに伴って、今まで「非同期にnew SugarInner({ template: await forward(template) });としたいができない」という状況が発生していたと思いますが、「new SugarInner({ template: { status: 'pending' } });」としてから、あとからsetTemplateで解決すればOKです。