Add flat map cache service (#14418)

## Context
Adding a new service that provides an abstract caching system for
FlatEntityMaps.
This takes care of cache invalidation and storing local and remote cache
for the map with retrieval after a comparison with map hash between
local and remote (redis).

## Implementation
Remote (redis) keys
- Flat map data:
`engine:workspace:flat-maps:{flatMapKey}:{workspaceId}:flat-map`
- Content hash:
`engine:workspace:flat-maps:{flatMapKey}:{workspaceId}:hash`

**Local Cache Hit**: If local hash matches Redis hash, return local data
**Remote Cache Hit**: If Redis has data with different hash, update
local cache
**Remote Cache Miss**: Recompute from database, store in Remote and
locally
**Invalidation**: Remove from Remote, triggering recomputation on next
access

## Usage
```typescript
@WorkspaceFlatMapCache('view') // redis key
export class WorkspaceFlatViewMapCacheService extends WorkspaceFlatMapCacheService<FlatViewMaps> {
  constructor(
    @InjectCacheStorage(CacheStorageNamespace.EngineWorkspace)
    cacheStorageService: CacheStorageService,
    @InjectRepository(ViewEntity)
    private readonly viewRepository: Repository<ViewEntity>,
  ) {
    super(cacheStorageService);
  }

  // only method to implement
  public async computeFlatMap(workspaceId: string): Promise<FlatViewMaps> {
    const views = await this.viewRepository.find({
      where: { workspaceId },
      relations: ['viewFields'],
      select: { viewFields: { id: true } },
    });

    return generateFlatViewMaps(views);
  }
}
```

```typescript
// 2 public methods, getExistingOrRecomputeFlatMaps to fetch the map and invalidateCache after a mutation 
  await this.workspaceFlatViewMapCacheService.invalidateCache(
    viewData.workspaceId,
  );

  const flatViewMaps =
    await this.workspaceFlatViewMapCacheService.getExistingOrRecomputeFlatMaps(
      workspaceId,
    );
```

## Multi-Pod Synchronization
- Each pod maintains local cache for performance
- SHA256 hash of flatMap content used for version comparison
- `invalidateCache()` reset Redis data, forcing other pods to refresh
when calling getExistingOrRecomputeFlatMaps

--- 
<img width="1072" height="325" alt="Screenshot 2025-09-11 at 15 04 48"
src="https://github.com/user-attachments/assets/ed6ce82c-db35-4a1b-8a4e-247b694e2ddf"
/>
<img width="1030" height="328" alt="Screenshot 2025-09-11 at 15 04 40"
src="https://github.com/user-attachments/assets/43a15789-7f27-4104-a9bb-bef19908a5cd"
/>

Next step: Implement a locking mechanism by reusing existing WithLock
decorator

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

@@ -0,0 +1,12 @@
+import { Module } from '@nestjs/common';
+import { TypeOrmModule } from '@nestjs/typeorm';
+
+import { ViewEntity } from 'src/engine/core-modules/view/entities/view.entity';
+import { WorkspaceFlatViewMapCacheService } from 'src/engine/core-modules/view/flat-view/services/workspace-flat-view-map-cache.service';
+
+@Module({
+  imports: [TypeOrmModule.forFeature([ViewEntity])],
+  providers: [WorkspaceFlatViewMapCacheService],
+  exports: [WorkspaceFlatViewMapCacheService],
+})
+export class FlatViewModule {}

packages/twenty-server/src/engine/core-modules/view/flat-view/services/workspace-flat-view-map-cache.service.ts

@@ -0,0 +1,46 @@
+import { Injectable } from '@nestjs/common';
+import { InjectRepository } from '@nestjs/typeorm';
+
+import { Repository } from 'typeorm';
+
+import { InjectCacheStorage } from 'src/engine/core-modules/cache-storage/decorators/cache-storage.decorator';
+import { CacheStorageService } from 'src/engine/core-modules/cache-storage/services/cache-storage.service';
+import { CacheStorageNamespace } from 'src/engine/core-modules/cache-storage/types/cache-storage-namespace.enum';
+import { ViewEntity } from 'src/engine/core-modules/view/entities/view.entity';
+import { type FlatViewMaps } from 'src/engine/core-modules/view/flat-view/types/flat-view-maps.type';
+import { generateFlatViewMaps } from 'src/engine/core-modules/view/flat-view/utils/generate-flat-view-maps.util';
+import { WorkspaceFlatMapCache } from 'src/engine/workspace-flat-map-cache/decorators/workspace-flat-map-cache.decorator';
+import { WorkspaceFlatMapCacheService } from 'src/engine/workspace-flat-map-cache/services/workspace-flat-map-cache.service';
+
+@Injectable()
+@WorkspaceFlatMapCache('view')
+export class WorkspaceFlatViewMapCacheService extends WorkspaceFlatMapCacheService<FlatViewMaps> {
+  constructor(
+    @InjectCacheStorage(CacheStorageNamespace.EngineWorkspace)
+    cacheStorageService: CacheStorageService,
+    @InjectRepository(ViewEntity)
+    private readonly viewRepository: Repository<ViewEntity>,
+  ) {
+    super(cacheStorageService);
+  }
+
+  protected async computeFlatMap({
+    workspaceId,
+  }: {
+    workspaceId: string;
+  }): Promise<FlatViewMaps> {
+    const views = await this.viewRepository.find({
+      where: {
+        workspaceId,
+      },
+      relations: ['viewFields'],
+      select: {
+        viewFields: {
+          id: true,
+        },
+      },
+    });
+
+    return generateFlatViewMaps(views);
+  }
+}

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

@@ -15,6 +15,7 @@ import { ViewFilterEntity } from 'src/engine/core-modules/view/entities/view-fil
 import { ViewGroupEntity } from 'src/engine/core-modules/view/entities/view-group.entity';
 import { ViewSortEntity } from 'src/engine/core-modules/view/entities/view-sort.entity';
 import { ViewEntity } from 'src/engine/core-modules/view/entities/view.entity';
+import { FlatViewModule } from 'src/engine/core-modules/view/flat-view/flat-view.module';
 import { ViewFieldResolver } from 'src/engine/core-modules/view/resolvers/view-field.resolver';
 import { ViewFilterGroupResolver } from 'src/engine/core-modules/view/resolvers/view-filter-group.resolver';
 import { ViewFilterResolver } from 'src/engine/core-modules/view/resolvers/view-filter.resolver';
@@ -48,6 +49,7 @@ import { WorkspaceMigrationV2Module } from 'src/engine/workspace-manager/workspa
     WorkspaceMetadataCacheModule,
     WorkspaceMigrationV2Module,
     ViewCacheModule,
+    FlatViewModule,
   ],
   controllers: [
     ViewController,