Design user-local IDE preference config for Base

[codeforester]

Goal

Design the user-local IDE preference layer that can sit above Base defaults and project manifest requirements.

Scope

• Decide whether user-local IDE preferences belong in ~/.base.d/config.yaml, ~/.base.d/ide.yaml, or another config file.
• Define how user preferences interact with project manifest settings.
• Preserve additive-only behavior and avoid becoming a general dotfile manager.
• Cover per-IDE enablement and personal settings preferences.
• Document migration and precedence rules.

Notes

This should happen after the project-level IDE bootstrap path is working. It is intentionally a later design step.