Refactor agent selection logic in InstallCommand

[pushpak1300]

Problem

When running boost:install, users are prompted twice to select code environments:

1. Editor selection: “Which code editors do you use?”
2. Agent selection: “Which agents need AI guidelines?”

Since most of the option support both MCP (editors) and AI guidelines (agents), users end up selecting the same environments twice creating a frustrating UX.

Scenario 1: First-Time User (No Saved Config)

Command: php artisan boost:install

Before	After
Editor prompt: Auto-detected from system Agent prompt: Auto-detected from system	Editor prompt: Auto-detected from system Agent prompt: ✨ Auto-derived from selected editors

Scenario 2: Returning User (Has Saved Config)

Command: php artisan boost:install

Before	After
Editor prompt: Previously saved editors Agent prompt: Previously saved agents	Editor prompt: Previously saved editors Agent prompt: ✨ Synced with current editor selection

Impact: Agent selection stays in sync with current editor choices, not stale saved config.

Scenario 3: With --ignore-guidelines

Command: php artisan boost:install --ignore-guidelines

Before	After
Editor prompt: Shown Agent prompt: Skipped	Editor prompt: Shown Agent prompt: Skipped

Scenario 4: With --ignore-mcp

Command: php artisan boost:install --ignore-mcp

Before	After
Editor prompt: Skipped Agent prompt: Saved config or auto-detected	Editor prompt: Skipped Agent prompt: Falls back to saved config