Add OllamaService connection check with factory and preferences
This change introduces a dedicated OllamaService for managing
communication with local Ollama instances:
- Add OllamaService with IsConnected() method to check Ollama
availability at localhost:11434
- Add OllamaServiceFactory as ProfileKeyedServiceFactory for
proper lifecycle management
- Add ollama.mojom interface defining kOllamaBaseUrl constant
and OllamaService mojo interface
- Add comprehensive unit tests for connection scenarios
- Add kBraveAIChatOllamaFetchEnabled preference for user control
- Register OllamaServiceFactory in browser context initialization
- Add preference to settings_private allowlist for WebUI access
- Add browser/ai_chat/ollama directory with factory implementation
- Wire up OllamaService dependency in content/browser layer
The service performs lightweight connection checks (1KB max) to
verify Ollama availability before enabling fetch functionality.
Andrea
a98761bc6f