feat(server): 新增申请核对预览快速建单接口与平台管理员判定统一

- reimbursements 新增 POST /application-preview-action，AI 工作台表格核对后直接走 UserAgentService 建单/提交，免去通用 Orchestrator 编排
- 平台管理员判定统一抽取 PLATFORM_ADMIN_IDENTITIES 常量，identity 与 role_codes 均支持 admin/superadmin，含 header 开关
- docker-compose 镜像补装 openssh-server
- 同步更新差旅/交通/通信等财务规则表与 reimbursements 端点测试

server/src/app/schemas/reimbursement.py

@@ -185,6 +185,29 @@ class ExpenseClaimActionResponse(BaseModel):
     status: str | None = None
 
 
+class ExpenseApplicationPreviewActionPayload(BaseModel):
+    source: str = Field(default="user_message", max_length=80)
+    user_id: str | None = Field(default=None, max_length=120)
+    conversation_id: str | None = Field(default=None, max_length=120)
+    message: str = Field(min_length=1, max_length=4000)
+    context_json: dict[str, Any] = Field(default_factory=dict)
+
+
+class ExpenseApplicationPreviewActionResult(BaseModel):
+    message: str
+    answer: str
+    suggested_actions: list[dict[str, Any]] = Field(default_factory=list)
+    risk_flags: list[str] = Field(default_factory=list)
+    requires_confirmation: bool = False
+    draft_payload: dict[str, Any] | None = None
+
+
+class ExpenseApplicationPreviewActionResponse(BaseModel):
+    status: str = "succeeded"
+    conversation_id: str | None = None
+    result: ExpenseApplicationPreviewActionResult
+
+
 class ExpenseClaimReturnPayload(BaseModel):
     reason: str | None = Field(default=None, max_length=500)
     reason_codes: list[str] = Field(default_factory=list, max_length=10)