feat(orm): add support for runtime virtual fields

[genu]

Adds support for @virtual fields that are computed at JavaScript runtime after query results are returned, complementing the existing @computed fields that are calculated at the database level.

Discord ref: https://discord.com/channels/1035538056146595961/1468213504724045905

Example

// Schema
model User {
    id Int @id
    firstName String
    lastName String
    fullName String @virtual
}

// Client
const client = new ZenStackClient(schema, {
    dialect,
    virtualFields: {
        User: {
            fullName: ({row}) => `${row.firstName} ${row.lastName}`,
        },
    },
});

Summary by CodeRabbit

• New Features

  • Runtime virtual fields: per-model virtual resolvers (sync/async) run with client/context and attach computed values to query results.

• Behavior Changes

  • Virtual fields are excluded from DB schema, selection filters, ordering, grouping and aggregates; selecting only virtuals triggers read-back behavior.
  • Result post-processing is now asynchronous and runs with request context; required dependencies for virtuals are fetched automatically.

• Types & SDK

  • Client options, generated schemas and model typings include virtual field metadata and typings.

• Tests

  • Comprehensive end-to-end tests for virtual fields.