feat: secure resource explanation subjects

src/govoplan_access/backend/api/v1/admin_schemas.py

@@ -541,6 +541,21 @@ class ResourceAccessExplanationResponse(BaseModel):
     provenance: list[AccessDecisionProvenanceItem] = Field(default_factory=list)
 
 
+class ResourceAccessExplanationSubjectItem(BaseModel):
+    id: str
+    email: str | None = None
+    display_name: str | None = None
+
+
+class ResourceAccessExplanationSubjectsResponse(BaseModel):
+    mode: Literal["current_user", "cross_user"]
+    can_select_other_users: bool
+    reason: str
+    source: str
+    required_scope: str | None = None
+    users: list[ResourceAccessExplanationSubjectItem] = Field(default_factory=list)
+
+
 class UserListResponse(PagedListResponse):
     users: list[UserAdminItem]