feat(box): add global sandbox scope option

Add a 'Global (shared by all)' option to the sandbox scope selector.
Uses a constant '{global}' template variable that always resolves to
'global', so all users and chats share one sandbox container.

Author: RockChinQ

src/langbot/pkg/box/service.py

@@ -176,7 +176,8 @@ def resolve_box_session_id(self, query: pipeline_query.Query) -> str:
             .get('local-agent', {})
             .get('box-session-id-template', '{launcher_type}_{launcher_id}')
         )
-        variables = query.variables or {}
+        variables = dict(query.variables or {})
+        variables.setdefault('global', 'global')
         return template.format_map(collections.defaultdict(lambda: 'unknown', variables))
 
     def build_skill_extra_mounts(self, query: pipeline_query.Query) -> list[dict]:

src/langbot/templates/metadata/pipeline/ai.yaml

@@ -127,6 +127,16 @@ stages:
         required: false
         default: "{launcher_type}_{launcher_id}"
         options:
+          - name: "{global}"
+            label:
+              en_US: Global (shared by all)
+              zh_Hans: 全局（所有人共享）
+              zh_Hant: 全域（所有人共用）
+              ja_JP: グローバル（全員共有）
+              vi_VN: Toàn cục (chia sẻ cho tất cả)
+              th_TH: ทั่วไป (แชร์ทั้งหมด)
+              es_ES: Global (compartido por todos)
+              ru_RU: Глобальный (общий для всех)
           - name: "{launcher_type}_{launcher_id}"
             label:
               en_US: Per chat (Recommended)