fix: DT Coach and HVE-Core Extensions create duplicate agents

### Component

VS Code Extension

### Bug Description

### Description

The 2 VS Code Extensions are resulting in duplicative agents getting installed:

1. HVE Core - Design Thinking
2. HVE Core

Below are the agents after installing these 2 extensions:

### Expected Behavior

### Objective:

To have both the "RPI Agent" and other "Task" related agents, along with the "DT Coach" agent. This will accomplish the desire to have a seamless handoff between the DT methods and the RPI framework.

The current workaround is to either:
1. forgo having the "RPI Agent" by installing only the "HVE Core - Design Thinking" extension
2. or to forgo having the "DT Coach" agent by installing only the "HVE Core" extension
3. or to install both extensions and deal with the duplicate agent modes
4. or to install the "HVE Core - All" extension to avoid duplication but get more agents than desired

### Proposed Outcome

Make the "DT Extension" leaner by only having the "DT Coach" and "DT Learning Tutor" agents. This way the "HVE Core" extension will introduce the "RPI Agent" and the other "Task" related agents.

### Steps to Reproduce

1. Install VS Code Extension: "HVE Core - Design Thinking"
2. Install VS Code Extension "HVE Core"

### Additional Context

_No response_

Start by comparing the contents of the “HVE Core - Design Thinking” and “HVE Core” VS Code extensions after installing both. Confirm which agents each extension contributes, then narrow the Design Thinking extension to “DT Coach” and “DT Learning Tutor”; done means the combined installation provides those agents plus the RPI and task-related agents without duplicates.

Written by the indexing model from the issue text.