fix(ai-ollama): accept tool_calls done reason

[swaraj017]

What it does

Fixes the Ollama integration treating done_reason: "tool_calls" as an unexpected response termination.

Ollama can use tool_calls as a valid done_reason when a model finishes a response by requesting tool execution. Previously, Theia only accepted stop, which caused the Ollama language model to throw:

Ollama stopped unexpectedly. Reason: tool_calls

This PR updates both done_reason checks in packages/ai-ollama/src/node/ollama-language-model.ts to accept both stop and tool_calls, while continuing to reject other unexpected reasons.

How to test

• Verified the change with git diff --check.
• Verified that the final diff contains only the intended changes in packages/ai-ollama/src/node/ollama-language-model.ts.
• Attempted to run yarn test:packages ai-ollama, but the test command could not be executed because the local Yarn/Corepack setup reported that the workspace package was missing from the lockfile and requested yarn install.

The existing packages/ai-ollama/src/node/ollama-language-model.spec.ts was left unchanged.

Follow-ups

None.

Breaking changes

• This PR introduces breaking changes and requires careful review. If yes, the breaking changes section in the [changelog](https://github.com/eclipse-theia/theia/blob/master/CHANGELOG.md) has been updated.

Attribution

None.

Review checklist

• As an author, I have thoroughly tested my changes and carefully followed [the review guidelines](https://github.com/eclipse-theia/theia/blob/master/doc/pull-requests.md#requesting-a-review)
• User-facing text is internationalized using the nls service (for details, please see the [Internationalization/Localization section](https://github.com/eclipse-theia/theia/blob/master/doc/coding-guidelines.md#internationalizationlocalization) in the Coding Guidelines)

Reminder for reviewers

• As a reviewer, I agree to behave in accordance with [the review guidelines](https://github.com/eclipse-theia/theia/blob/master/doc/pull-requests.md#reviewing)