Adds a new 'pi config' command with a TUI to list and toggle package
resources (extensions, skills, prompts, themes).
- Displays resources grouped by source (packages, user, project)
- Subgroups by resource type (Extensions, Skills, Prompts, Themes)
- Toggle enabled/disabled state with space
- Filter resources by typing
- Supports +pattern for force-include, !pattern for exclude
- Properly reads exclusion patterns from settings.json
fixes#938
150128fd2c