docs: Langfuse integration (#4245)

Add doc for Langfuse integration

docs/docs/Integrations/Notion/_category_.json

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docs/docs/Integrations/integrations-assemblyai.md

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 title: AssemblyAI
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docs/docs/Integrations/integrations-langfuse.md

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+---
+title: Langfuse
+sidebar_position: 2
+slug: /integrations-langfuse
+---
+
+import Tabs from '@theme/Tabs';
+import TabItem from '@theme/TabItem';
+
+# Integrate Langfuse with Langflow
+
+[Langfuse](https://langfuse.com/) is an observability and analytics platform specifically designed for language models and AI applications.
+
+This guide walks you through how to configure Langflow to collect [tracing](https://langfuse.com/docs/tracing) data about your flow executions and automatically send the data to Langfuse.
+
+## Prerequisites
+
+- A project in Langflow with a runnable flow
+- A Langfuse Cloud account in any [data region](https://langfuse.com/faq/all/cloud-data-regions)
+- A Langfuse organization and project
+
+## Create Langfuse project credentials
+
+1. In Langfuse, go to your project settings, and then create a new set of API keys.
+
+2. Copy the following API key information:
+
+   - Secret Key
+   - Public Key
+   - Host URL
+
+## Set your Langfuse credentials as environment variables
+
+Set your Langfuse project credentials as environment variables in the same environment where you run Langflow.
+
+You can use any method you prefer to set environment variables.
+The following examples show how to set environment variables in a terminal session (Linux or macOS) and in a command prompt session (Windows):
+
+<Tabs>
+
+<TabItem value="linux-macos" label="Linux or macOS" default>
+```
+export LANGFUSE_SECRET_KEY=SECRET_KEY
+export LANGFUSE_PUBLIC_KEY=PUBLIC_KEY
+export LANGFUSE_HOST=HOST_URL
+```
+</TabItem>
+
+<TabItem value="windows" label="Windows" default>
+```
+set LANGFUSE_SECRET_KEY=SECRET_KEY
+set LANGFUSE_PUBLIC_KEY=PUBLIC_KEY
+set LANGFUSE_HOST=HOST_URL
+```
+</TabItem>
+
+</Tabs>
+
+Replace `SECRET_KEY`, `PUBLIC_KEY`, and `HOST_URL` with the API key information you copied from Langfuse.
+
+## Start Langflow and run a flow
+
+1. Start Langflow in the same terminal or environment where you set the environment variables:
+
+    ```bash
+    python -m langflow run
+    ```
+
+2. In Langflow, open and existing project, and then run a flow.
+
+## View tracing data in Langfuse
+
+Langflow automatically collects and sends tracing data about the flow execution to Langfuse.
+You can view the collected data in your Langfuse project dashboard.
+
+## Disable the Langfuse integration
+
+To disable the Langfuse integration, remove the environment variables you set in the previous steps and restart Langflow.

docs/docs/Integrations/integrations-langsmith.md

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 title: LangSmith
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docs/docs/Integrations/integrations-langwatch.md

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 title: LangWatch
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 slug: /integrations-langwatch
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