fix(weixin): remove _LIVE_ADAPTERS session reuse to avoid aiohttp timeout error

[Scott1743]

Problem

In aiohttp 3.13.5, context manager fails when a session created with is reused from a context via (where ).

The optimization that reuses an existing adapter+session across calls causes intermittent errors:

Fix

Always create a fresh per call instead of reusing . This is slightly less efficient but eliminates the non-deterministic timeout failures.

Changes

• : remove session reuse logic in , always create fresh session

[alt-glitch]

Likely duplicate of #14481 and #13350 — same root cause: aiohttp session reuse in weixin direct send causes timeout errors across event loops. Multiple prior PRs target the same fix (#12810, #13361, #18890).

[Scott1743]

@alt-glitch Thanks for the context. Agreed on the root cause — this is the same pattern. If any of the prior PRs (#12810, #13361, #18890) is already merged or close to merge, happy to close this as duplicate and defer. If not, this PR stands.

[teknium1]

Automated hermes-sweeper review: current main already fixes the Weixin direct-send aiohttp timeout failure this PR targets.

Evidence:

• gateway/platforms/weixin.py:2286 now gates _LIVE_ADAPTERS reuse: the live adapter is reused only when its _send_session is open and send_session._loop is asyncio.get_running_loop(); otherwise send_weixin_direct() falls through to the fresh one-shot aiohttp.ClientSession path at gateway/platforms/weixin.py:2315.
• gateway/platforms/weixin.py:1287 disables aiohttp's built-in ClientTimeout for the Weixin send session, with the inline comment tying it to the exact Timeout context manager should be used inside a task failure mode.
• gateway/platforms/weixin.py:381 and gateway/platforms/weixin.py:405 enforce API timeouts with asyncio.wait_for() instead of aiohttp timeout kwargs.
• tests/gateway/test_weixin.py:1106 covers the timeout-contract migration by asserting Weixin API helpers no longer forward aiohttp timeout kwargs and still raise on slow responses.

The PR's broader approach of removing live-adapter reuse entirely is no longer needed for the reported cross-event-loop timeout failure.