perf: add database indexes, implement caching, enforce permission guards, and sanitize external URLs

paperless-backend/src/settings/settings.controller.ts

@@ -327,14 +327,11 @@ export class SettingsController {
       const settings = await this.corrSettingRepo.find();
       const settingsMap = new Map(settings.map(s => [s.CorrespondentId, s]));
 
-      for (const pc of paperlessCorrs) {
-        if (!settingsMap.has(pc.id)) {
-          const newSetting = this.corrSettingRepo.create({
-            CorrespondentId: pc.id,
-            AgrarmonitorId: null,
-          });
-          await this.corrSettingRepo.save(newSetting);
-        }
+      const newSettings = paperlessCorrs
+        .filter((pc: any) => !settingsMap.has(pc.id))
+        .map((pc: any) => this.corrSettingRepo.create({ CorrespondentId: pc.id, AgrarmonitorId: null }));
+      if (newSettings.length > 0) {
+        await this.corrSettingRepo.insert(newSettings);
       }
 
       // Re-fetch merged