webui : fix circular dependency between chat.service.ts and models.svelte.ts

[Juste-Leo2]

Overview

This PR fixes a circular dependency between the chat.service.ts and models.svelte.ts files by using direct imports for models.service and props.service.

Additional Information

Similar to PR #22557, I used Sentrux to investigate the dependency loop issues.

The Circular Dependency Path:

1. Starting point in models.svelte.ts:

   import { ModelsService, PropsService } from '$lib/services';

2. The routing through the index, which imports ./chat.service:

   export { ChatService } from './chat.service';

3. The loop back within chat.service.ts, which imports from models.svelte.ts:

   import { modelsStore } from '$lib/stores/models.svelte';

Context for models.service and props.service usage:
These imports are utilized in specific locations, such as:

• At line 367:

  const props = await PropsService.fetchForModel(modelId);

• From lines 113 to 115:

  if (serverStore.isRouterMode) return null;
  const props = serverStore.props;

Validation:
I performed a manual check to ensure everything resolves correctly:

PS I:\github-repo\llama.cpp\tools\server\webui> npm run check

> llama-server-webui@1.0.0 check
> svelte-kit sync && svelte-check --tsconfig ./tsconfig.json

Loading svelte-check in workspace: i:\github-repo\llama.cpp\tools\server\webui
Getting Svelte diagnostics...

svelte-check found 0 errors and 0 warnings

Requirements

• I have read and agree with the [contributing guidelines](https://github.com/ggml-org/llama.cpp/blob/master/CONTRIBUTING.md)
• AI usage disclosure: YES
  • I used Antigravity to navigate the project and better identify the loop.
  • I discussed the issue with an AI to help select the correct elements for direct import.
  • I used AI to translate the PR into English (written by me in French) and improve the formatting and readability. :)