feat(workflow): scaffold core workflowVersion entity + trigger cache (phase 0) (#21674)

## What

**Phase 0 (scaffold)** of migrating `workflowVersion` data to **core**.
Gated by `IS_WORKFLOW_VERSION_IN_CORE_ENABLED` with **no behavior
change** — nothing reads or writes the new core entity yet.

## Plan

`workflowVersion` becomes a thin **workspace shell** over a core entity
(the `dashboard`/`pageLayout` pattern), so navigation, the metadata
relations, and the record UI keep working while the heavy data
(`triggers`, `steps`) lives in core. Trigger dispatch will derive from
active core versions via a per-workspace cache, letting us **eliminate**
the denormalized `workflowAutomatedTrigger` object. `workflow` and
`workflowRun` stay as workspace objects.

Phases: **0 — scaffold (this PR)** → A — backfill + dual-write → B —
switch reads to core → C — drop the workspace `trigger`/`steps` columns
+ the `workflowAutomatedTrigger` object.

## Included
- **Core `WorkflowVersionEntity`** (`extends WorkspaceRelatedEntity`) —
stores version data, with triggers as an **array** (`triggers:
WorkflowTrigger[]`), a long-due shape change. Storage only: dispatch
reads the primary trigger, so behavior stays single-trigger for now.
- **Fast create-table instance command** for `core."workflowVersion"`
(v2.19.0).
- **`IS_WORKFLOW_VERSION_IN_CORE_ENABLED`** feature flag.
- **Per-workspace automated-trigger cache provider** deriving
CRON/DATABASE_EVENT dispatch from the active version's trigger —
groundwork for removing `workflowAutomatedTrigger`.

## Notes
- `WorkspaceRelatedEntity`, **not** `SyncableEntity`: this is user
runtime data (like `connectedAccount`/`apiKey`/`file`), not
application-manifest metadata.
- No frontend behavior; the generated `FeatureFlagKey` enums are updated
to include the new flag.

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

@@ -100,6 +100,7 @@ import { AddDisplayFieldsToApplicationRegistrationFastInstanceCommand } from './
 import { BackfillDisplayFieldsOnApplicationRegistrationSlowInstanceCommand } from './2-19/2-19-instance-command-slow-1783073776591-backfill-display-fields-on-application-registration';
 import { BackfillIsFeaturedOnApplicationRegistrationSlowInstanceCommand } from './2-19/2-19-instance-command-slow-1783120000000-backfill-is-featured-on-application-registration';
 import { AllowServerScopedFileFastInstanceCommand } from 'src/database/commands/upgrade-version-command/2-20/2-20-instance-command-fast-1783499671541-allow-server-scoped-file';
+import { CreateWorkflowVersionCoreTableFastInstanceCommand } from './2-20/2-20-instance-command-fast-1783512000000-create-workflow-version-core-table';
 
 export const INSTANCE_COMMANDS = [
   AddViewFieldGroupIdIndexOnViewFieldFastInstanceCommand,
@@ -202,4 +203,5 @@ export const INSTANCE_COMMANDS = [
   AddPendingMimeCheckToFileFastInstanceCommand,
   BackfillIsFeaturedOnApplicationRegistrationSlowInstanceCommand,
   AllowServerScopedFileFastInstanceCommand,
+  CreateWorkflowVersionCoreTableFastInstanceCommand,
 ];