feat(server): workspace opt-out of root-domain directory listing (#22423)

## What

Lets a workspace opt out of being surfaced in the multi-workspace
root-domain (app.twenty.com) picker via **email-domain discovery**.

Adds `isDirectoryListingEnabled` (default `true`) on the workspace. When
`false`, the workspace is filtered out of the approved-access-domain
branch of `findAvailableWorkspacesByEmail`, so a user whose email domain
matches an approved access domain no longer sees the workspace in the
sign-up picker.

## Scope of the opt-out (deliberately narrow)

The filter is applied **only** to the approved-access-domain discovery
source:

- **Members** (`availableWorkspacesForSignIn`) — never filtered; they
keep access.
- **Explicit invitations** — never filtered; the intent is one-to-one.
- **Approved-access-domain discovery** — the only "listing" source,
gated by the flag.

A hidden workspace stays fully reachable by members and invited users
via the direct workspace subdomain; it just isn't advertised in the
global picker.

> Open question for review: do we also want a stronger mode that hides
the workspace from the root-domain picker even for existing members
(forcing them to use the subdomain directly)? That would additionally
filter the member/invitation sources and is a larger behavior change —
not included here.

## Changes

**Backend**
- `workspace.entity.ts` — new `isDirectoryListingEnabled` column
(`@Field`, default `true`).
- `user-workspace.service.ts` — filter the approved-access-domain branch
on the flag.
- `update-workspace-input.ts` — expose the field on `updateWorkspace`.
- `workspace.service.ts` — `PermissionFlagType.SECURITY` (same as the
other discovery/security toggles).
- Fast instance command adding the column (default `true`, so no
existing workspace is hidden).

**Frontend**
- Settings > Security: a **"List in workspace directory"** toggle (shown
only in multi-workspace mode) that flips the flag via `updateWorkspace`,
mirroring the existing `isInternalMessagesImportEnabled` toggle.
- Threaded the field through the current-user fragment,
`CurrentWorkspace` type, and mock data.
- Regenerated the metadata + client-sdk GraphQL types
(`generated-metadata`, `twenty-client-sdk/.../generated`) — generated
against a server booted from this branch.

## Verification

- `tsgo` typecheck: 0 errors. `oxlint`: 0/0. `oxfmt`: clean.
- Codegen diff verified to contain **only** the new field (no unrelated
drift).
- Tests not run locally; CI covers unit/integration + the
codegen/migration freshness checks.

---------

Co-authored-by: claude[bot] <41898282+claude[bot]@users.noreply.github.com>

packages/twenty-server/src/database/commands/upgrade-version-command/instance-commands.constant.ts

@@ -88,6 +88,7 @@ import { MigrateAiModelPreferencesSlowInstanceCommand } from 'src/database/comma
 import { AddFolderImportToMessageFolderPendingSyncActionFastInstanceCommand } from './2-15/2-15-instance-command-fast-1781714499016-add-folder-import-to-message-folder-pending-sync-action';
 import { AddViewKanbanColumnWidthFastInstanceCommand } from './2-15/2-15-instance-command-fast-1781900000000-add-view-kanban-column-width';
 import { AddPendingQuestionMessageIdToAgentChatThreadFastInstanceCommand } from 'src/database/commands/upgrade-version-command/2-19/2-19-instance-command-fast-1811000000000-add-pending-question-to-agent-chat-thread';
+import { AddWorkspaceDiscoverabilityToWorkspaceFastInstanceCommand } from './2-19/2-19-instance-command-fast-1820000001000-add-workspace-discoverability-to-workspace';
 import { DropMetadataStandardOverridesColumnFastInstanceCommand } from './2-20/2-20-instance-command-fast-1825000000000-drop-metadata-standard-overrides-column';
 
 export const INSTANCE_COMMANDS = [
@@ -176,6 +177,7 @@ export const INSTANCE_COMMANDS = [
   AddTsVectorFieldMetadataIdToSearchFieldMetadataFastInstanceCommand,
   BackfillTsVectorFieldMetadataIdOnSearchFieldMetadataSlowInstanceCommand,
   AddPendingQuestionMessageIdToAgentChatThreadFastInstanceCommand,
+  AddWorkspaceDiscoverabilityToWorkspaceFastInstanceCommand,
   AddMetadataOverridesColumnFastInstanceCommand,
   BackfillMetadataOverridesSlowInstanceCommand,
   AddLastStreamErrorToAgentChatThreadFastInstanceCommand,