feat(app-dev): sync error hints, flatEntity labels, dev-mode summary UI, and docs (#21252)

Split out of #21240 — all remaining app-dev improvements. Stacked on
#21251 (review/merge that first).

- Actionable recovery hints on failed syncs; unified diff renderer;
`--dry-run` guard.
- Return `flatEntity` on update/delete sync actions and unify the diff
label.
- Summarize the dev-mode entity list unless `--verbose`.
- Docs: syncing & recovery guide + dry-run + open-an-issue prompt.
- Live execution mode for synced logic functions; clearer manifest
warnings.

<img width="1018" height="700" alt="image"
src="https://github.com/user-attachments/assets/5e9ce19e-0f1d-4f99-8524-4e118bde932b"
/>

packages/twenty-sdk/src/cli/operations/dev-once.ts

@@ -16,10 +16,12 @@ import { ClientService } from '@/cli/utilities/client/client-service';
 import { ConfigService } from '@/cli/utilities/config/config-service';
 import { formatSyncActionsSummary } from '@/cli/utilities/dev/orchestrator/steps/format-sync-actions-summary';
 import { formatManifestValidationErrors } from '@/cli/utilities/error/format-manifest-validation-errors';
+import { getSyncErrorRecoveryHint } from '@/cli/utilities/error/get-sync-error-recovery-hint';
 import { serializeError } from '@/cli/utilities/error/serialize-error';
 import { FileUploader } from '@/cli/utilities/file/file-uploader';
 import { runSafe } from '@/cli/utilities/run-safe';
 import { APP_ERROR_CODES, type CommandResult } from '@/cli/types';
+import chalk from 'chalk';
 
 export type AppDevOnceOptions = {
   appPath: string;
@@ -44,6 +46,15 @@ const reportMetadataChanges = (
   }
 };
 
+const appendRecoveryHint = (
+  message: string,
+  errorMessage: string | undefined,
+): string => {
+  const hint = getSyncErrorRecoveryHint(errorMessage);
+
+  return hint ? `${message}\n\n${hint}` : message;
+};
+
 const innerAppDevOnce = async (
   options: AppDevOnceOptions,
 ): Promise<CommandResult<AppDevOnceResult>> => {
@@ -95,7 +106,7 @@ const innerAppDevOnce = async (
   }
 
   for (const warning of manifestResult.warnings) {
-    onProgress?.(`⚠ ${warning}`);
+    onProgress?.(chalk.yellow(`⚠ ${warning}`));
   }
 
   onProgress?.('Building application files...');
@@ -148,13 +159,13 @@ const innerAppDevOnce = async (
 
       const message = errorEvents
         ? errorEvents.map((event) => event.message).join('\n')
-        : `Dry run failed with error: ${serializeError(dryRunResult.error)}`;
+        : `Dry run failed with error: ${dryRunResult.message ?? 'Unknown error'}`;
 
       return {
         success: false,
         error: {
           code: APP_ERROR_CODES.SYNC_FAILED,
-          message,
+          message: appendRecoveryHint(message, dryRunResult.message),
         },
       };
     }
@@ -254,13 +265,13 @@ const innerAppDevOnce = async (
 
     const message = errorEvents
       ? errorEvents.map((event) => event.message).join('\n')
-      : `Sync failed with error: ${serializeError(syncResult.error)}`;
+      : `Sync failed with error: ${syncResult.message ?? 'Unknown error'}`;
 
     return {
       success: false,
       error: {
         code: APP_ERROR_CODES.SYNC_FAILED,
-        message,
+        message: appendRecoveryHint(message, syncResult.message),
       },
     };
   }

packages/twenty-sdk/src/cli/operations/install.ts

@@ -2,7 +2,6 @@ import { ApiService } from '@/cli/utilities/api/api-service';
 import { readManifestFromFile } from '@/cli/utilities/build/manifest/manifest-reader';
 import { ConfigService } from '@/cli/utilities/config/config-service';
 import { formatManifestValidationErrors } from '@/cli/utilities/error/format-manifest-validation-errors';
-import { serializeError } from '@/cli/utilities/error/serialize-error';
 import { runSafe } from '@/cli/utilities/run-safe';
 import { APP_ERROR_CODES, type CommandResult } from '@/cli/types';
 
@@ -40,7 +39,7 @@ const innerAppInstall = async (
 
     const message = errorEvents
       ? errorEvents.map((event) => event.message).join('\n')
-      : `Install failed with error: ${serializeError(result.error)}`;
+      : `Install failed with error: ${result.message ?? 'Unknown error'}`;
 
     return {
       success: false,