[General] Add options to curate the "Open in" list.

**Mood:** 😊
**Category:** General

Add options to curate the "Open in" list.
The list (Terminal, PowerShell, Command Prompt, Bash) only supports adding apps. Add a way to hide/show defaults so the list can be curated — e.g. a "More" dialog to add custom tools and toggle visibility per entry. I want to remove some of the defaults, not just add others.

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| Field | Value |
| --- | --- |
| App version | 0.2.34 |
| OS | Windows 10.0.26200 |
| Theme | GitHub |
| Path | /chat |
| Tenure | Week 2 |

Start by locating the implementation of the “Open in” list and the existing add-app settings, then trace how default entries are defined and displayed. Done means users can add custom tools and independently hide or show each default entry, with the curated list reflected in the interface.

Written by the indexing model from the issue text.