refactor(weixin-ilink): 措辞纠正 —「会话过期」→「会话被 iLink 拒绝」（零逻辑改动）

事实（主人 2026-10-03 确认）：iLink 的 bot token 是长期凭据（一个月前扫码的仍可用）；errcode=-14 是 iLink 侧拒绝/作废该会话，不是时间性过期；且至今未观测到真实 -14（当日全部日志 0 次）。此前代码把这些写成「过期」，属沿用的旧命名，现纠正。
- 纯改名/文案：ErrSessionExpired→ErrSessionRejected、errSessionExpired→errcodeSessionRejected、expired/expiredToken→rejected/rejectedToken、markExpired/expiredLocked/expiredState→markRejected/rejectedLocked/rejectedState；409 错误码 session_expired→session_rejected
- 行为一字未改：显式标记 / Connect 不假 OK / 面板 needsRescan+lastError / 扫码或换新 token 即清除 全部保留
- 微信协议自身的「二维码过期」与 auth 的 JWT/refresh 过期一律未动（那些是真·时间性过期）
- Docs/api-client v0.39 补事实说明；顺手收尾 3 处残留注释（admin.go / channelbridge/inbound.go / readloop_test.go）

internal/services/channelbridge/inbound.go

@@ -24,7 +24,7 @@ import (
 // messages alone.
 //
 // When the read path returns with readCtx still alive, the adapter stopped
-// reading on its own — today that is the weixin-iLink expired session
+// reading on its own — today that is the weixin-iLink rejecting the session
 // (errcode=-14, see plugins/channels/weixin_ilink/session_state.go), which used to
 // leave the bridge claiming the channel was connected while it could no longer
 // deliver anything. A cancelled readCtx is a deliberate stop (bridge Stop or a