feat: Individual page export in Markdown and HTML formats (#80)

* fix maths node

* render default html width

* Add page export module
* with support for html and markdown exports

* Page export UI
* Add PDF print too

* remove unused import

apps/server/src/integrations/export/dto/export-dto.ts

@@ -0,0 +1,26 @@
+import {
+  IsBoolean,
+  IsIn,
+  IsNotEmpty,
+  IsOptional,
+  IsString,
+} from 'class-validator';
+
+export enum ExportFormat {
+  HTML = 'html',
+  Markdown = 'markdown',
+}
+
+export class ExportPageDto {
+  @IsString()
+  @IsNotEmpty()
+  pageId: string;
+
+  @IsString()
+  @IsIn(['html', 'markdown'])
+  format: ExportFormat;
+
+  @IsOptional()
+  @IsBoolean()
+  includeFiles?: boolean;
+}