[voice] Add REST endpoint to get LLM tools

[florian-h05]

No description provided.

[florian-h05]

@holgerfriedrich Can you please have a look at this PR? It's only a new REST endpoint and I need it for the chat UI (which BTW is finished, just waiting for this endpoint).

[Copilot]

Pull request overview

Adds a new REST API endpoint under the existing voice REST resource to expose available LLM tools (id/label/description) for clients, along with DTO/mapping support and a unit test.

Changes:

• Extend VoiceResource with GET /voice/llmtools returning a JSON list of tools (localized via Accept-Language).
• Add LLMToolDTO and LLMToolMapper to convert LLMTool domain objects to REST DTOs.
• Update VoiceResourceTest to cover the new endpoint.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
bundles/org.openhab.core.io.rest.voice/src/main/java/org/openhab/core/io/rest/voice/internal/VoiceResource.java	Injects LLMToolRegistry and adds GET /llmtools endpoint returning mapped DTOs.
bundles/org.openhab.core.io.rest.voice/src/main/java/org/openhab/core/io/rest/voice/internal/LLMToolMapper.java	New mapper from LLMTool to LLMToolDTO.
bundles/org.openhab.core.io.rest.voice/src/main/java/org/openhab/core/io/rest/voice/internal/LLMToolDTO.java	New OpenAPI-annotated DTO representing an LLM tool for REST responses.
bundles/org.openhab.core.io.rest.voice/src/test/java/org/openhab/core/io/rest/voice/internal/VoiceResourceTest.java	Updates constructor usage and adds a unit test for getLLMTools.

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[florian-h05]

@holgerfriedrich Addressed Copilot review 👍