fix(ollama): preserve tools across agent loop turns

[dvd233]

Description

Fixes #13254.

Ollama chat requests only attached tool definitions when the last converted message had the user role. After Continue executed the first tool, the next Agent-mode request ended with a tool result, so tools disappeared from the request body and Ollama could not select the next tool.

Attach configured tools whenever CompletionOptions.tools is non-empty. This matches Ollama's current multi-turn agent-loop examples, which pass the available tools on every loop iteration, including after appending tool results.

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Checklist

• I've read the contributing guide
• The relevant docs, if any, have been updated or created (not applicable: no user-facing API or configuration change)
• The relevant tests, if any, have been updated or created

Screen recording or screenshot

Not applicable; this is an outbound request-construction bug covered by a focused regression test.

Tests

• Regression proof on unchanged source: the new test fails because body.tools is undefined, while the 10 existing Ollama tests pass
• npm test --prefix core -- --runInBand llm/llms/Ollama.test.ts (11/11 passed)
• npm run tsc:check --prefix core
• Prettier check for both changed files
• git diff --check

[github-actions]

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[dvd233]

I have read the CLA Document and I hereby sign the CLA