docs: fix session type filters - use Upload Sessions not System

The i18n key is session.System but the UI label is "Upload Sessions".
Revert System back to Upload Sessions, keep the added All filter.

Author: nowgnuesLee

packages/backend.ai-webui-docs/src/en/session_page/session_page.md

@@ -25,7 +25,7 @@ For more detailed information about resource panels and their metrics, please re
 ## Session list
 
 The 'Sessions' section displays a list of all active and completed compute sessions.
-You can filter sessions by type — `All`, `Interactive`, `Batch`, `Inference`, or `System` — and switch between
+You can filter sessions by type — `All`, `Interactive`, `Batch`, `Inference`, or `Upload Sessions` — and switch between
 `Running` and `Finished` tabs to manage sessions.
 
 By default, you can view the following columns: session name, status, allocated resources (AI Accelerators, CPU, Memory),

packages/backend.ai-webui-docs/src/ja/session_page/session_page.md

@@ -25,7 +25,7 @@ For more detailed information about resource panels and their metrics, please re
 ## Session list
 
 The 'セッション' section displays a list of all active and completed compute sessions.
-You can filter sessions by type — `All`, `Interactive`, `Batch`, `Inference`, or `System` — and switch between
+You can filter sessions by type — `All`, `Interactive`, `Batch`, `Inference`, or `Upload Sessions` — and switch between
 `Running` and `Finished` tabs to manage sessions.
 
 By default, you can view the following columns: session name, status, allocated resources (AI Accelerators, CPU, Memory),

packages/backend.ai-webui-docs/src/ko/session_page/session_page.md

@@ -23,7 +23,7 @@ Backend.AI에서 `세션(session)`은 사용자가 할당된 자원을 사용하
 ## 세션 목록
 
 '세션' 섹션에는 모든 활성 및 완료된 연산 세션의 목록이 표시됩니다.
-`All`, `Interactive`, `Batch`, `Inference`, 또는 `System` 유형별로 세션을 필터링할 수 있으며,
+`All`, `Interactive`, `Batch`, `Inference`, 또는 `업로드 세션` 유형별로 세션을 필터링할 수 있으며,
 `실행중` 탭과 `종료됨` 탭을 전환하여 세션을 관리할 수 있습니다.
 
 기본적으로 세션 이름, 상태, 할당된 자원(AI 가속기, CPU, 메모리), 경과 시간을 확인할 수 있으며, 슈퍼관리자의 경우 에이전트 및 소유자 이메일도 표시됩니다.

packages/backend.ai-webui-docs/src/th/session_page/session_page.md

@@ -25,7 +25,7 @@ For more detailed information about resource panels and their metrics, please re
 ## Session list
 
 The 'เซสชัน' section displays a list of all active and completed compute sessions.
-You can filter sessions by type — `All`, `Interactive`, `Batch`, `Inference`, or `System` — and switch between
+You can filter sessions by type — `All`, `Interactive`, `Batch`, `Inference`, or `Upload Sessions` — and switch between
 `Running` and `Finished` tabs to manage sessions.
 
 By default, you can view the following columns: session name, status, allocated resources (AI Accelerators, CPU, Memory),