fix(inbound): keep polling while turns are active

[NewFuture]

Upstream source

Exact mirror of Tencent/openclaw-weixin#228 by @NewFuture.

• Original branch: NewFuture/openclaw-weixin:fix/inbound-polling
• Original base: cef0bfc390393f716903e16d50408118047f87e0
• Preserved head: 0e3e5868d8a2b2856d5b58cf5be8dc114a4d7cec
• Current target base at mirror creation: 4feec89ff2b40c93578a96f6325bdd536ad9d38e
• Commit history and authorship are unchanged.

Upstream intent

Keep long polling active while OpenClaw processes an active turn, preserve ordinary-message ordering until Core admission, and give /approve plugin: an independent admission lane.

Local review status

This mirror is intentionally a Draft. The exact upstream head merges cleanly into the current target, and focused tests, typecheck, and build passed during review, but the following issues remain unresolved:

• abort can discard queued messages after their cursor has already been persisted;
• same-user queued messages can overwrite the singleton context token before earlier work starts;
• active processing is detached during shutdown and can continue after the monitor resolves;
• backlog growth is unbounded;
• the admission lifecycle API names do not match either the supported OpenClaw 2026.5.12 surface or the newer renamed API.

Related upstream #187 is tracked separately as todo-rebase; it is not included in this mirror. Original discussion and review history remain on the upstream PR.