feat: enhance global settings update with data loss prevention

- Added safeguards to prevent overwriting non-empty arrays with empty arrays during global settings updates, specifically for the 'projects' field.
- Implemented logging for updates to assist in diagnosing accidental wipes of critical settings.
- Updated tests to verify that projects are preserved during logout transitions and that theme changes are ignored if a project wipe is attempted.
- Enhanced the settings synchronization logic to ensure safe handling during authentication state changes.

apps/server/src/routes/settings/routes/update-global.ts

@@ -11,7 +11,7 @@
 import type { Request, Response } from 'express';
 import type { SettingsService } from '../../../services/settings-service.js';
 import type { GlobalSettings } from '../../../types/settings.js';
-import { getErrorMessage, logError } from '../common.js';
+import { getErrorMessage, logError, logger } from '../common.js';
 
 /**
  * Create handler factory for PUT /api/settings/global
@@ -32,6 +32,18 @@ export function createUpdateGlobalHandler(settingsService: SettingsService) {
         return;
       }
 
+      // Minimal debug logging to help diagnose accidental wipes.
+      if ('projects' in updates || 'theme' in updates || 'localStorageMigrated' in updates) {
+        const projectsLen = Array.isArray((updates as any).projects)
+          ? (updates as any).projects.length
+          : undefined;
+        logger.info(
+          `Update global settings request: projects=${projectsLen ?? 'n/a'}, theme=${
+            (updates as any).theme ?? 'n/a'
+          }, localStorageMigrated=${(updates as any).localStorageMigrated ?? 'n/a'}`
+        );
+      }
+
       const settings = await settingsService.updateGlobalSettings(updates);
 
       res.json({