feat(openai): port /responses/compact account support flow (PR #1555)

将 vansour/sub2api#1555 的 OpenAI compact 能力建模手工移植到当前 main：账号
级 compact 状态/auto-force_on-force_off 模式、compact-only 模型映射、调度器
tier 分层（已支持 > 未知 > 已知不支持）、管理后台 compact 主动探测，以及对应
i18n/状态徽章。普通 /responses 流量行为不变，无数据库迁移。

frontend/src/types/index.ts

@@ -767,8 +767,8 @@ export interface Account {
   platform: AccountPlatform
   type: AccountType
   credentials?: Record<string, unknown>
-  // Extra fields including Codex usage and model-level rate limits (Antigravity smart retry)
-  extra?: (CodexUsageSnapshot & {
+  // Extra fields including Codex usage, OpenAI compact capability, and model-level rate limits.
+  extra?: (CodexUsageSnapshot & OpenAICompactState & {
     model_rate_limits?: Record<string, { rate_limited_at: string; rate_limit_reset_at: string }>
     antigravity_credits_overages?: Record<string, { activated_at: string; active_until: string }>
   } & Record<string, unknown>)
@@ -940,6 +940,16 @@ export interface CodexUsageSnapshot {
   codex_usage_updated_at?: string // Last update timestamp
 }
 
+export type OpenAICompactMode = 'auto' | 'force_on' | 'force_off'
+
+export interface OpenAICompactState {
+  openai_compact_mode?: OpenAICompactMode
+  openai_compact_supported?: boolean
+  openai_compact_checked_at?: string
+  openai_compact_last_status?: number
+  openai_compact_last_error?: string
+}
+
 export interface CreateAccountRequest {
   name: string
   notes?: string | null