🧠 feat: Reasoning UI for Agents (#5904)

* chore: bump https-proxy-agent and @librechat/agents

* refactor: Improve error logging in OllamaClient for API fetch failures

* feat: Add DeepSeek provider support and enhance provider name handling

* refactor: Use Providers.OLLAMA constant for model name check in fetchModels function

* feat: Enhance formatAgentMessages to handle reasoning content type

* feat: OpenRouter Agent Reasoning

* hard work and dedicationgit add .env.example :)

* fix: Handle Google social login with missing last name

Social login with Google was previously displaying 'undefined' when
a user's last name was empty or not provided.

Changes:
- Conditionally render last name only if it exists
- Prevent displaying 'undefined' when last name is missing

* fix: add missing file endings for developers yml,yaml and log

---------

Co-authored-by: Mohamed Al-Duraji <mbalduraji@college.harvard.edu>
Co-authored-by: Deepak Kendole <deepakdpk101@gmail.com>
Co-authored-by: Peter Rothlaender <peter.rothlaender@ginkgo.com>

api/server/controllers/agents/callbacks.js

@@ -199,6 +199,22 @@ function getDefaultHandlers({ res, aggregateContent, toolEndCallback, collectedU
         aggregateContent({ event, data });
       },
     },
+    [GraphEvents.ON_REASONING_DELTA]: {
+      /**
+       * Handle ON_REASONING_DELTA event.
+       * @param {string} event - The event name.
+       * @param {StreamEventData} data - The event data.
+       * @param {GraphRunnableConfig['configurable']} [metadata] The runnable metadata.
+       */
+      handle: (event, data, metadata) => {
+        if (metadata?.last_agent_index === metadata?.agent_index) {
+          sendEvent(res, { event, data });
+        } else if (!metadata?.hide_sequential_outputs) {
+          sendEvent(res, { event, data });
+        }
+        aggregateContent({ event, data });
+      },
+    },
   };
 
   return handlers;