Fix race create sessione su CPX: ready solo dopo MediaMTX.

I nodi cloud restano in provisioning finché :9997 risponde; retry su create_path e 503 retryable se l’ingest è ancora irraggiungibile.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/services/sessions/create.rb

@@ -58,6 +58,13 @@ module Sessions
       session
     rescue Streams::NodeRegistry::NoCapacityError => e
       raise Teams::EntitlementError.new(e.message, code: "stream_capacity_exhausted")
+    rescue Faraday::ConnectionFailed, Faraday::TimeoutError => e
+      raise Streams::IngestUnavailableError, "Ingest temporaneamente non disponibile (#{e.class})"
+    rescue Mediamtx::Client::Error => e
+      if e.message.to_s.match?(/failed to open|Connection refused|Timeout|timed out/i)
+        raise Streams::IngestUnavailableError, e.message
+      end
+      raise
     end
 
     private