dynamically infer many to many primary key types

[l0g1x]

previously, many-to-many primary key types where being hardcoded to string()

[Copilot]

Pull Request Overview

This PR dynamically infers many-to-many primary key types instead of hardcoding them to string(), and updates the many-to-many join table configuration accordingly.

• Infers primary key types using mapPrismaTypeToZero.
• Introduces explicit checks for primary key existence with clear error messages.
• Refactors relationship definitions to use locally stored primary key fields.

Files not reviewed (1)

• src/tests/snapshots/generator.test.ts.snap: Language not supported

Comments suppressed due to low confidence (2)

src/mappers/schemaMapper.ts:98

• [nitpick] Since modelA_pkField is already verified to exist earlier, consider simplifying to 'destField: [modelA_pkField.name]' for clarity.

destField: modelA_pkField.name ? [modelA_pkField.name] : [],

src/mappers/schemaMapper.ts:104

• [nitpick] Since modelB_pkField is already verified to exist earlier, consider simplifying to 'destField: [modelB_pkField.name]' for clarity.

destField: modelB_pkField.name ? [modelB_pkField.name] : [],

[elledienne]

Thanks for the PR @l0g1x! I am going to merge #36, which supersedes your PR (adds tests and a couple of other minor things), but appreciate you looking into it and providing a fix