fix the same rate_limit default in pi-embedded-runner probe gate

Two more sites in run.ts used "rate_limit" as the null-coalesce
default from resolveProfilesUnavailableReason. Update both to
"unknown" and add "unknown" to the transient cooldown probe
eligibility check so single-provider setups can still recover.

src/agents/pi-embedded-runner/run.ts

@@ -553,7 +553,7 @@ export async function runEmbeddedPiAgent(
             resolveProfilesUnavailableReason({
               store: authStore,
               profileIds,
-            }) ?? "rate_limit"
+            }) ?? "unknown"
           );
         }
         const classified = classifyFailoverReason(params.message);
@@ -669,14 +669,15 @@ export async function runEmbeddedPiAgent(
           ? (resolveProfilesUnavailableReason({
               store: authStore,
               profileIds: autoProfileCandidates,
-            }) ?? "rate_limit")
+            }) ?? "unknown")
           : null;
         const allowTransientCooldownProbe =
           params.allowTransientCooldownProbe === true &&
           allAutoProfilesInCooldown &&
           (unavailableReason === "rate_limit" ||
             unavailableReason === "overloaded" ||
-            unavailableReason === "billing");
+            unavailableReason === "billing" ||
+            unavailableReason === "unknown");
         let didTransientCooldownProbe = false;
 
         while (profileIndex < profileCandidates.length) {