feat(figue): integrate @standard-schema/spec to replace zod

[CorentinTh]

Closes #5

[Copilot]

Pull Request Overview

This PR integrates the @standard-schema/spec library to replace Zod in configuration validation. Key changes include updating type definitions in figue.types.ts, replacing the buildConfigSchema function with a new synchronous validateConfig implementation in figue.ts, and modifying tests in figue.test.ts to support multiple validation libraries.

Reviewed Changes

Copilot reviewed 5 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/index.ts	Removed the export for buildConfigSchema and now only exports defineConfig.
src/figue.types.ts	Updated type definitions to use StandardSchemaV1 and its InferOutput method.
src/figue.ts	Replaced buildConfigSchema with validateConfig and adjusted the configuration merging logic.
src/figue.test.ts	Added a test case to ensure support for multiple validation libraries (e.g., Zod and Valibot).
src/figue.errors.ts	Updated error creation to use StandardSchemaV1.Issue instead of ZodIssue.

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Comments suppressed due to low confidence (1)

src/figue.ts:58

• The current check in isConfigDefinitionElement strictly requires a '~standard' property, which may break integration with alternative validation libraries (such as valibot) expected in the tests. Consider refactoring this check to support a polymorphic approach for schema validation.

&& '~standard' in config.schema