feat(twenty-orm): introduce WorkspaceScopedRepository for core/metadata workspace-scoped entities (#20953)

## Summary

Adds a third tenancy enforcement layer for entities that live in shared
schemas (`core`, `metadata`) and carry a `workspaceId` column —
previously the only safeguard at this layer was developer discipline
(remembering to put `workspaceId` in every WHERE clause).

### The three layers, after this PR

| Layer | Scope | How it's enforced |
|---|---|---|
| 1. Workspace data | per-workspace schema (companies, people, custom
objects) | `twentyORMManager.getRepository(workspace, E)` — physical
isolation (own data source) |
| 2. Metadata | shared `metadata` schema (objectMetadata, fieldMetadata,
views, roles…) | Flat-entity-maps cache — workspace-scoped in-memory
map, lookups by id within it |
| 3. Core (new) | shared `core` schema (agent threads/turns/messages,
app tokens, etc.) | `WorkspaceScopedRepository<T>` — `workspaceId` is a
required positional argument on every read/write |

## What's in the PR

### The wrapper
(`packages/twenty-server/src/engine/twenty-orm/workspace-scoped-repository/`)
- `WorkspaceScopedRepository<T extends WorkspaceScopedEntity>` — wraps a
TypeORM `Repository<T>`, requires `workspaceId` on every
`find`/`findOne`/`findOneOrFail`/`update`/`delete`/`softDelete`/`insert`/`save`/`count`
call, merging it into the WHERE or stamping it on the entity.
`createQueryBuilder` is an explicit escape hatch (caller scopes
manually).
- Provided via Nest DI with
`@InjectWorkspaceScopedRepository(EntityClass)` and the
`provideWorkspaceScopedRepository(EntityClass)` provider factory.
- 19 unit tests cover the merge behavior, override-on-conflict, and the
array-where (OR) case.

### Lint enforcement
(`packages/twenty-oxlint-rules/rules/prefer-workspace-scoped-repository.ts`)
- New `twenty/prefer-workspace-scoped-repository` rule (level:
**error**).
- Blacklist of entity names: raw `@InjectRepository(E)` is rejected if
`E` is on the list.
- Initial list: `AgentTurnEntity`, `AgentMessageEntity`,
`AgentMessagePartEntity`, `AgentChatThreadEntity`,
`AgentTurnEvaluationEntity`, `AgentEntity`.
- Designed to grow over time as more consumers are migrated.
- 5 rule tests.

### Migration in this PR
All consumers of the six blacklisted entities, including:
- AI agent / chat / monitor resolvers, services, and jobs
- `AgentService`, `AiAgentRoleService`, `AiAgentWorkflowAction`,
`ApplicationService`, `WorkspaceFlatAgentMapCacheService`
- Admin-panel chat (migrated where the lookup is workspace-known; one
documented `eslint-disable` on the threadId-discovery lookup that
necessarily precedes the `allowImpersonation` permission check)
- `AiAgentRoleService` unit spec updated to mock the scoped wrapper

## Future work (deliberately not in this PR)

A standalone audit identified ~14 additional `core`/`metadata` entities
with `workspaceId` that currently use raw `@InjectRepository` and could
be added to the blacklist. Notable candidates: `UserWorkspaceEntity` (42
sites), `AppTokenEntity` (10), `FileEntity` (7),
`BillingCustomerEntity`/`BillingSubscriptionEntity` (~22 combined). Each
should be its own PR — the migration is mechanical but the surface is
wide.

## Test plan
- [x] `npx nx typecheck twenty-server` — clean
- [x] `npx nx lint twenty-server` — 0 warnings, 0 errors
- [x] `npx jest workspace-scoped-repository` — 19/19 pass
- [x] `npx nx test twenty-oxlint-rules` — 215/215 pass
- [x] `npx jest src/engine/metadata-modules/ai` — 44/44 pass
- [ ] Manual smoke: end-to-end AI agent chat send/receive (reviewer)
- [ ] Manual smoke: AI agent monitor — list turns, run evaluation
(reviewer)
- [ ] Manual smoke: admin-panel chat thread inspection (reviewer)

packages/twenty-server/src/modules/messaging/message-participant-manager/message-participant-manager.module.ts

@@ -10,6 +10,7 @@ import { RoleTargetEntity } from 'src/engine/metadata-modules/role-target/role-t
 import { RoleEntity } from 'src/engine/metadata-modules/role/role.entity';
 import { WorkspaceFeatureFlagsMapCacheService } from 'src/engine/metadata-modules/workspace-feature-flags-map-cache/workspace-feature-flags-map-cache.service';
 import { ObjectMetadataRepositoryModule } from 'src/engine/object-metadata-repository/object-metadata-repository.module';
+import { provideWorkspaceScopedRepository } from 'src/engine/twenty-orm/workspace-scoped-repository/provide-workspace-scoped-repository';
 import { GetDataFromCacheWithRecomputeService } from 'src/engine/workspace-cache-storage/services/get-data-from-cache-with-recompute.service';
 import { WorkspaceCacheStorageService } from 'src/engine/workspace-cache-storage/workspace-cache-storage.service';
 import { WorkspaceCacheModule } from 'src/engine/workspace-cache/workspace-cache.module';
@@ -53,6 +54,7 @@ import { TimelineActivityWorkspaceEntity } from 'src/modules/timeline/standard-o
     WorkspaceFeatureFlagsMapCacheService,
     WorkspaceCacheStorageService,
     GetDataFromCacheWithRecomputeService,
+    provideWorkspaceScopedRepository(FeatureFlagEntity),
   ],
   exports: [MessagingMessageParticipantService],
 })