feat: TTLock API server selector (EU vs China) + pass apiServer to agent

- Add api_server column to hotel_ttlock_config (migration 053)
- GET/PATCH config includes apiServer field
- issue-card passes apiServer to agent command
- Agent: WriteCardCmd.apiServer optional, all API calls use it
- TTLockPage: radio buttons EU/China with hint about 404 error

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib/api.ts

@@ -1091,6 +1091,7 @@ export interface TTLockConfig {
   isEnabled:   boolean
   clientId:    string
   cardSectors: string
+  apiServer:   string
 }
 
 export interface TTLockConfigUpdate {
@@ -1098,6 +1099,7 @@ export interface TTLockConfigUpdate {
   clientId?:     string
   clientSecret?: string
   cardSectors?:  string
+  apiServer?:    string
 }
 
 export interface RoomLockMapping {