perf(backend): jsdom、happy-domをやめて軽量な実装にし、メモリ削減・高速化 (#16885)

* wip

* Update packages/backend/src/server/api/endpoints/i/update.ts

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update packages/backend/src/core/FetchInstanceMetadataService.ts

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* remove some packages

* コミット漏れ

* clean up

* fix

* Update MfmService.ts

* fix

* fix

* Update MfmService.ts

* wip

* rename

* Update packages/backend/src/core/MfmService.ts

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update packages/backend/src/core/MfmService.ts

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update packages/backend/src/core/MfmService.ts

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update packages/backend/src/core/MfmService.ts

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update packages/backend/src/core/activitypub/ApRendererService.ts

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update packages/backend/src/core/MfmService.ts

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update packages/backend/src/core/MfmService.ts

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update MfmService.ts

* Update CHANGELOG.md

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

CHANGELOG.md

@@ -7,7 +7,8 @@
 -
 
 ### Server
--
+- Enhance: メモリ使用量を削減しました
+- Enhance: ActivityPubアクティビティを送信する際のパフォーマンス向上
 
 
 ## 2025.11.1