feat(coding-agent): add pi config TUI to manage resources

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

packages/coding-agent/src/cli/args.ts

@@ -184,6 +184,7 @@ ${chalk.bold("Commands:")}
   ${APP_NAME} remove <source> [-l]     Remove extension source from settings
   ${APP_NAME} update [source]          Update installed extensions (skips pinned sources)
   ${APP_NAME} list                     List installed extensions from settings
+  ${APP_NAME} config                   Open TUI to enable/disable package resources
 
 ${chalk.bold("Options:")}
   --provider <name>              Provider name (default: google)