feat: emit metadata events for schema changes with actor context for webhooks (#17622)

## Summary

This PR adds **metadata eventing**: when schema metadata
(objectMetadata, fieldMetadata, view, viewField, etc.) is created,
updated, or deleted, we now emit events that can trigger webhooks and
future audit logs. It also adds **actor context** (`userId`,
`workspaceMemberId`) to those events so subscribers can attribute
changes to a user or API key.

## What changed

### 1. Metadata eventing (first commit)

- **MetadataEventEmitter**  
New service that emits batch events after successful workspace
migrations. Event names follow `metadata.{entity}.{action}` (e.g.
`metadata.objectMetadata.created`, `metadata.fieldMetadata.updated`).
- **MetadataEventsToDbListener**  
Listens for metadata events and enqueues webhook delivery via
`CallWebhookJobsForMetadataJob`.
- **Event types** (twenty-shared)  
`MetadataEventAction`, `MetadataEventBatch`, and record event types for
create/update/delete.
- **WorkspaceMigrationValidateBuildAndRunService**  
Calls the metadata event emitter after running migrations so all
metadata changes (from any module) emit events from a single place.
- **Create events**  
Sourced from the create action payload (`flatEntity` /
`flatFieldMetadatas`) because `fromToAllFlatEntityMaps` does not provide
a before/after diff for creates. Update/delete events still use the
fromToAllFlatEntityMaps comparison.

### 2. Actor context (second commit)

- **MetadataEventEmitter**  
Accepts optional `actorContext` (`userId`, `workspaceMemberId`) and
includes it on emitted batch events.
- **WorkspaceMigrationValidateBuildAndRunService**  
Passes `actorContext` from the request into the metadata event emitter.
- **Metadata resolvers & services**  
All metadata modules resolve `@AuthUser({ allowUndefined: true })` and
`@AuthUserWorkspaceId()` and pass `userId` and `workspaceMemberId`
through to the migration/event pipeline. Both are optional so
API-key–authenticated requests (no user) still emit events without a
user identity.
  
Shared some questions on Discord about the PR.

---------

Co-authored-by: Félix Malfait <felix.malfait@gmail.com>
Co-authored-by: prastoin <paul@twenty.com>

packages/twenty-server/src/engine/core-modules/core-engine.module.ts

@@ -63,6 +63,7 @@ import { RoleModule } from 'src/engine/metadata-modules/role/role.module';
 import { RowLevelPermissionModule } from 'src/engine/metadata-modules/row-level-permission-predicate/row-level-permission.module';
 import { SubscriptionsModule } from 'src/engine/subscriptions/subscriptions.module';
 import { TrashCleanupModule } from 'src/engine/trash-cleanup/trash-cleanup.module';
+import { MetadataEventEmitterModule } from 'src/engine/metadata-event-emitter/metadata-event-emitter.module';
 import { WorkspaceEventEmitterModule } from 'src/engine/workspace-event-emitter/workspace-event-emitter.module';
 import { ChannelSyncModule } from 'src/modules/connected-account/channel-sync/channel-sync.module';
 import { DashboardModule } from 'src/modules/dashboard/dashboard.module';
@@ -104,6 +105,7 @@ import { FileModule } from './file/file.module';
     PostgresCredentialsModule,
     WorkflowApiModule,
     WorkspaceEventEmitterModule,
+    MetadataEventEmitterModule,
     ActorModule,
     TelemetryModule,
     AdminPanelModule,