feat(core): requests 兼容异步垫片 + 同步/异步桥

- core/aiohttp_compat.py：以 requests 同形 API（post/get + Response.json/text/
  status_code/raise_for_status + HTTPError/RequestException/Timeout）实现异步请求，
  使既有 requests 风格代码可「加 await + async def」最小改动迁移；4xx/5xx 不抛、
  仅 raise_for_status() 抛（与 requests 语义一致，保住风控判断逻辑）
- core/async_bridge.py：run_sync(coro) 经常驻后台事件循环线程执行协程并阻塞等待，
  供迁移期同步调用方（遗留 Flask 路由/线程池）复用异步实现

验证：pytest 16/16；ruff All checks passed；pyright 0 errors。

tests/test_aiohttp_compat.py

@@ -0,0 +1,82 @@
+# -*- coding: utf-8 -*-
+"""兼容垫片与同步桥测试。"""
+import asyncio
+
+import pytest
+from aiohttp import web
+
+from core import aiohttp_compat as req
+from core import async_bridge
+
+
+@pytest.fixture()
+async def server():
+    app = web.Application()
+
+    async def ok(request):
+        return web.json_response({'code': 200, 'data': 'hi'})
+
+    async def notfound(request):
+        return web.json_response({'code': 404}, status=404)
+
+    async def echo_post(request):
+        body = await request.text()
+        return web.json_response({'got': body, 'ua': request.headers.get('User-Agent')})
+
+    app.router.add_get('/ok', ok)
+    app.router.add_get('/nf', notfound)
+    app.router.add_post('/echo', echo_post)
+
+    runner = web.AppRunner(app)
+    await runner.setup()
+    site = web.TCPSite(runner, '127.0.0.1', 0)
+    await site.start()
+    port = site._server.sockets[0].getsockname()[1]
+    try:
+        yield f'http://127.0.0.1:{port}'
+    finally:
+        await runner.cleanup()
+
+
+async def test_get_json(server):
+    r = await req.get(server + '/ok')
+    assert r.status_code == 200
+    assert r.json() == {'code': 200, 'data': 'hi'}
+    assert 'code' in r.text
+    r.raise_for_status()  # 200 不抛
+
+
+async def test_4xx_does_not_raise_until_raise_for_status(server):
+    r = await req.get(server + '/nf')
+    assert r.status_code == 404          # 请求本身不抛（同 requests）
+    assert r.json() == {'code': 404}
+    with pytest.raises(req.HTTPError):
+        r.raise_for_status()
+
+
+async def test_post_headers_forwarded(server):
+    r = await req.post(server + '/echo', data={'params': 'x'}, headers={'User-Agent': 'ua-test'})
+    body = r.json()
+    assert body['ua'] == 'ua-test'
+    assert 'params' in body['got']
+
+
+async def test_network_error_raises_request_exception():
+    with pytest.raises(req.RequestException):
+        await req.get('http://127.0.0.1:1/nope', timeout=1)
+
+
+def test_bridge_runs_coro_from_sync():
+    async def coro():
+        await asyncio.sleep(0.01)
+        return 42
+
+    assert async_bridge.run_sync(coro()) == 42
+
+
+async def test_bridge_rejects_inside_loop():
+    async def coro():
+        return 1
+
+    with pytest.raises(RuntimeError):
+        async_bridge.run_sync(coro())