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',