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/middleware/breaker.py

@@ -25,9 +25,11 @@ class BreakerGate:
         except Exception as exc:
             raise GovernanceBackendError(f"熔断后端故障(try_enter): {exc}") from exc
 
-    async def record_success(self, entry: GateDecision) -> GateUpdate:
+    async def record_success(
+        self, entry: GateDecision, *, count_attempt: bool = True
+    ) -> GateUpdate:
         try:
-            return await self._gate.record_success(entry)
+            return await self._gate.record_success(entry, count_attempt=count_attempt)
         except GovernanceBackendError:
             raise
         except Exception as exc: