feat(app-dev): add dry-run preview to dev sync (#21251)

Split out of #21240. Stacked on #21250 (review/merge that first).

`yarn twenty dev --once --dry-run` computes the migration plan and
prints the diff **without applying anything** (no migration, no
app-record update, no SDK generation). Also renders the diff on a normal
`dev --once` sync.

<img width="646" height="179" alt="image"
src="https://github.com/user-attachments/assets/59f3ddcd-2a5b-4b8a-b21a-c659abe16af0"
/>

packages/twenty-sdk/src/cli/utilities/api/api-service.ts

@@ -73,13 +73,16 @@ export class ApiService {
     return this.applicationApi.createDevelopmentApplication(...args);
   }
 
-  syncApplication(manifest: Manifest): Promise<
+  syncApplication(
+    manifest: Manifest,
+    options?: { dryRun?: boolean },
+  ): Promise<
     ApiResponse<{
       applicationUniversalIdentifier: string;
       actions: SyncAction[];
     }>
   > {
-    return this.applicationApi.syncApplication(manifest);
+    return this.applicationApi.syncApplication(manifest, options);
   }
 
   uninstallApplication(universalIdentifier: string): Promise<ApiResponse> {

packages/twenty-sdk/src/cli/utilities/api/application-api.ts

@@ -252,7 +252,10 @@ export class ApplicationApi {
     }
   }
 
-  async syncApplication(manifest: Manifest): Promise<
+  async syncApplication(
+    manifest: Manifest,
+    options?: { dryRun?: boolean },
+  ): Promise<
     ApiResponse<{
       applicationUniversalIdentifier: string;
       actions: SyncAction[];
@@ -260,15 +263,15 @@ export class ApplicationApi {
   > {
     try {
       const mutation = `
-        mutation SyncApplication($manifest: JSON!) {
-          syncApplication(manifest: $manifest) {
+        mutation SyncApplication($manifest: JSON!, $dryRun: Boolean) {
+          syncApplication(manifest: $manifest, dryRun: $dryRun) {
             applicationUniversalIdentifier
             actions
           }
         }
       `;
 
-      const variables = { manifest };
+      const variables = { manifest, dryRun: options?.dryRun ?? false };
 
       const response: AxiosResponse = await this.client.post(
         '/metadata',

packages/twenty-sdk/src/cli/utilities/dev/orchestrator/steps/__tests__/format-sync-actions-summary.spec.ts

@@ -10,6 +10,12 @@ describe('formatSyncActionsSummary', () => {
     ]);
   });
 
+  it('reports no changes when actions are missing from the response', () => {
+    expect(formatSyncActionsSummary(undefined)).toEqual([
+      { message: 'No metadata changes', status: 'info' },
+    ]);
+  });
+
   it('summarizes created, updated and deleted actions with their identifiers', () => {
     const events = formatSyncActionsSummary([
       {

packages/twenty-sdk/src/cli/utilities/dev/orchestrator/steps/format-sync-actions-summary.ts

@@ -24,15 +24,17 @@ const getActionLabel = (action: SyncAction): string => {
 };
 
 export const formatSyncActionsSummary = (
-  actions: SyncAction[],
+  actions: SyncAction[] | undefined,
 ): OrchestratorStateStepEvent[] => {
-  if (actions.length === 0) {
+  const definedActions = actions ?? [];
+
+  if (definedActions.length === 0) {
     return [{ message: 'No metadata changes', status: 'info' }];
   }
 
   const counts = { create: 0, update: 0, delete: 0 };
 
-  for (const action of actions) {
+  for (const action of definedActions) {
     counts[action.type] += 1;
   }
 
@@ -46,7 +48,7 @@ export const formatSyncActionsSummary = (
     { message: `Metadata changes: ${summaryParts.join(', ')}`, status: 'info' },
   ];
 
-  const visibleActions = actions.slice(0, MAX_DETAIL_LINES);
+  const visibleActions = definedActions.slice(0, MAX_DETAIL_LINES);
 
   for (const action of visibleActions) {
     events.push({
@@ -55,7 +57,7 @@ export const formatSyncActionsSummary = (
     });
   }
 
-  const hiddenCount = actions.length - visibleActions.length;
+  const hiddenCount = definedActions.length - visibleActions.length;
 
   if (hiddenCount > 0) {
     events.push({