feat: config option to display intermediate assistant text between tool calls

[laurajustinevermore]

Problem

When my agent produces substantive text responses between tool calls in a single turn, that text is visible in ADE but silently discarded in Discord (and presumably other channels). PR #547 treats all mid-turn assistant text as scratch notes, but my agent writes real user-facing information in those intermediate responses.

Proposed solution

A config option like:

     features:
       display:
         showIntermediateText: true

to let users opt in to receiving mid-turn assistant text.

There have been numerous times that I've had to ask my agent follow up questions because I didn't realise the question had been answered between tool calls. Right now I have to check the ADE to see if there's additional messages, which isn't ideal as it disrupts workflow.