feat: feed selector health and demote in-call failed sources

RetryMW keeps a per-call failure map (local, never instance state):
a source failing twice in one call yields to the next candidate.
Attempt outcomes feed OutcomeAwareSelector behind a swallow-and-warn
guard; ResultInvalid and provider-rejected paths record success with
count_attempt=False so the breaker window stays clean. Same accounting
applied in EmbeddingClient.

src/polygateway/embedding.py

@@ -303,7 +303,8 @@ class EmbeddingClient:
         """终态异常的门控写回(与 RetryMW 同口径): 坏结果/网关健康拒绝 ≠ 坏服务
         → 记成功;网关没响应的拒绝若持探针则归还。"""
         if isinstance(exc, ResultInvalidError) or exc.status_code is not None:
-            await self._record_quietly(self._breaker.record_success(entry))
+            # M2.5 §3.1: 记成功但不计失败率窗口样本(坏结果/坏请求 ≠ 坏服务)
+            await self._record_quietly(self._breaker.record_success(entry, count_attempt=False))
         elif entry.is_probe:
             await self._record_quietly(self._breaker.release_probe(entry))