Enhance FlowPilot skills map

- Added migration to register ~12 missing agent skills for visitors and admin (browse products, check availability, browse services, newsletter subscribe, blog browse, subscriber management, booking availability, orders, inventory, blog categories, chat feedback, webinar registration)
- Updated agent-execute to support new module mappings (ecommerce) and extended handlers for new skills
- Introduced inventory and back-in-stock flows, visitor-facing product browsing, booking checks, and admin capabilities for newsletters, subscribers, orders, and inventory
- Wired new skills to existing modules (products, booking, blog, newsletter, webinars, analytics) and prepared for Shopify-like ecommerce UX

X-Lovable-Edit-ID: edt-3b258d22-c27a-4d21-aa0a-39fe1d75f67d
Co-authored-by: magnusfroste <38864257+magnusfroste@users.noreply.github.com>

Author: lovable-dev[bot]