[InferenceSnippets] Add endpointUrl option

[Wauplin]

Add an option to pass a custom endpoint URL for inference snippets generation.

snippets.getInferenceSnippets(
	model,
	selectedProvider,
	{
		hfModelId: ...,
		providerId: ...,
		status: "live",
		task: pipeline,
	},
	{
		streaming,
		endpointURL: "http://localhost:8080/v1",
	}
)

cc @gary149

[Copilot]

Pull Request Overview

This PR adds support for specifying a custom endpoint URL when generating inference snippets.

• Adds an "endpointUrl" option to the snippet generation functions.
• Updates fixture files and templates for shell, Python, and JavaScript clients.
• Modifies test cases and documentation to reflect the new option.

Reviewed Changes

Copilot reviewed 18 out of 18 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
packages/tasks-gen/snippets-fixtures/*	New fixture files using the custom endpoint URL in shell, Python, and JS examples.
packages/tasks-gen/scripts/generate-snippets-fixtures.ts	Adds a new test case for the custom endpoint option.
packages/inference/src/snippets/templates/*	Updates templates across languages to conditionally include the custom endpoint URL.
packages/inference/src/snippets/getInferenceSnippets.ts	Integrates the endpointUrl option into snippet request arguments and token replacement logic.
packages/inference/README.md	Updates documentation to showcase usage of the new endpoint URL option.

[HuggingFaceDocBuilderDev]

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