fix(auth): prevent stale ModelStates inheritance from disabled auth entries

When an auth file is deleted and re-created with the same path/ID, the
new auth could inherit stale ModelStates (cooldown/backoff) from the
previously disabled entry, preventing it from being routed.

Gate runtime state inheritance (ModelStates, LastRefreshedAt,
NextRefreshAfter) on both existing and incoming auth being non-disabled
in Manager.Update and Service.applyCoreAuthAddOrUpdate.

Closes #2061

sdk/cliproxy/auth/conductor.go

@@ -832,8 +832,10 @@ func (m *Manager) Update(ctx context.Context, auth *Auth) (*Auth, error) {
 			auth.Index = existing.Index
 			auth.indexAssigned = existing.indexAssigned
 		}
-		if len(auth.ModelStates) == 0 && len(existing.ModelStates) > 0 {
-			auth.ModelStates = existing.ModelStates
+		if !existing.Disabled && existing.Status != StatusDisabled && !auth.Disabled && auth.Status != StatusDisabled {
+			if len(auth.ModelStates) == 0 && len(existing.ModelStates) > 0 {
+				auth.ModelStates = existing.ModelStates
+			}
 		}
 	}
 	auth.EnsureIndex()