refactor(import): remove non-functional DOCX/PDF/Confluence import stubs

These import paths relied on the private EE module that was deleted from
the repo. In the community build they either threw 'enterprise license'
(DOCX/PDF) or silently no-op'd (Confluence). The frontend buttons were
already removed in 38064064; this cleans up the dead backend stubs.

- import.service.ts: drop processDocx/processPdf methods, their dispatcher
  branches, the pageId computation + insertPage spread, and the now-unused
  moduleRef param/ModuleRef import
- file-import-task.service.ts: drop the Confluence branch and the now-unused
  moduleRef param/ModuleRef import
- import.controller.ts: restrict file extensions to .md/.html and zip
  sources to generic/notion; update the error message accordingly
- file.utils.ts: remove Confluence from the FileImportSource enum
- features.ts: remove the unused CONFLUENCE_IMPORT/DOCX_IMPORT/PDF_IMPORT
  feature keys

The isConfluenceImport logic in import-attachment.service.ts is intentionally
left in place (real shared attachment-parsing code, not a stub); its removal
is a separate, riskier refactor.

apps/server/src/integrations/import/services/file-import-task.service.ts

@@ -32,7 +32,6 @@ import {
 import { executeTx } from '@docmost/db/utils';
 import { BacklinkRepo } from '@docmost/db/repos/backlink/backlink.repo';
 import { ImportAttachmentService } from './import-attachment.service';
-import { ModuleRef } from '@nestjs/core';
 import { PageService } from '../../../core/page/services/page.service';
 import { ImportPageNode } from '../dto/file-task-dto';
 import { EventEmitter2 } from '@nestjs/event-emitter';
@@ -54,7 +53,6 @@ export class FileImportTaskService {
     private readonly backlinkRepo: BacklinkRepo,
     @InjectKysely() private readonly db: KyselyDB,
     private readonly importAttachmentService: ImportAttachmentService,
-    private moduleRef: ModuleRef,
     private eventEmitter: EventEmitter2,
     @Inject(AUDIT_SERVICE) private readonly auditService: IAuditService,
   ) {}
@@ -115,27 +113,6 @@ export class FileImportTaskService {
         });
       }
 
-      if (fileTask.source === FileImportSource.Confluence) {
-        let ConfluenceModule: any;
-        try {
-          // eslint-disable-next-line @typescript-eslint/no-require-imports
-          ConfluenceModule = require('./../../../ee/confluence-import/confluence-import.service');
-        } catch (err) {
-          this.logger.error(
-            'Confluence import requested but EE module not bundled in this build',
-          );
-          return;
-        }
-        const confluenceImportService = this.moduleRef.get(
-          ConfluenceModule.ConfluenceImportService,
-          { strict: false },
-        );
-
-        await confluenceImportService.processConfluenceImport({
-          extractDir: tmpExtractDir,
-          fileTask,
-        });
-      }
       try {
         await this.updateTaskStatus(fileTaskId, FileTaskStatus.Success, null);
         await cleanupTmpFile();