Remove tools API and probably don't store them in the database at all. Rely on app

[rusenask]

The app creation now also creates tools in the database but they aren't really used in the normal path. Let's have tools defined only in the app, this simplifies our operations.

Currently blocking API call for tools: https://github.com/helixml/helix/blob/main/api/pkg/controller/inference.go#L32-L35

Streaming API tools: https://github.com/helixml/helix/blob/main/api/pkg/controller/inference.go#L68-L71

We run them directly based on the app, example:

func (c *Controller) evaluateToolUsageStream(ctx context.Context, user *types.User, req openai.ChatCompletionRequest, opts *ChatCompletionOptions) (*openai.ChatCompletionStream, bool, error) {
	_, sessionID, interactionID := oai.GetContextValues(ctx)

	selectedTool, isActionable, ok, err := c.selectAndConfigureTool(ctx, user, req, opts)
	if err != nil {
		return nil, false, fmt.Errorf("failed to select and configure tool: %w", err)
	}

	if !ok {
		return nil, false, nil
	}

	lastMessage := getLastMessage(req)
	history := types.HistoryFromChatCompletionRequest(req)

	stream, err := c.ToolsPlanner.RunActionStream(ctx, sessionID, interactionID, selectedTool, history, lastMessage, isActionable.Api)
	if err != nil {
		return nil, false, fmt.Errorf("failed to perform action: %w", err)
	}

	return stream, true, nil
}