docs: add Tuning Engines integration

[cerebrixos]

Adds a Flowise integration page for using Tuning Engines as an OpenAI-compatible inference endpoint, plus a summary entry next to the existing LiteLLM docs.

[gemini-code-assist]

Code Review

This pull request introduces documentation for integrating Tuning Engines with Flowise, including a new entry in the summary and a detailed guide on configuring OpenAI-compatible chat models. Feedback suggests refining the instructions to use exact UI labels like 'Base Path' and 'Model Name', and clarifying the use of the 'Connect Credential' system for managing API keys to better align with the Flowise user interface.

[gemini-code-assist]

To improve clarity for Flowise users, it is recommended to use the exact labels found in the user interface. In the 'ChatOpenAI' or 'OpenAI Compatible' nodes, the fields are typically labeled Base Path and Model Name. Additionally, API keys are managed through the Connect Credential system rather than being entered directly into the node configuration.

Suggested change

	- Set `BasePath` to `https://api.tuningengines.com/v1`
	- Set the API key to your Tuning Engines inference key
	- Set the model name to a model alias enabled for that key, for example `gpt-4o-mini`
	- Set Base Path to https://api.tuningengines.com/v1\n- Under Connect Credential, create or select an OpenAI API credential and use your Tuning Engines inference key as the API Key\n- Set Model Name to a model alias enabled for that key, for example gpt-4o-mini