Add per-feature license control for enterprise

TofuPilot now supports per-feature licensing, giving you more flexibility to pay only for what you need instead of upgrading to a fixed plan tier.

• Added per-feature licensing for SSO, SCIM, and team management instead of requiring a full enterprise plan upgrade
• Added admin tools for configuring self-hosted instances with custom feature sets and expiration dates
• Renamed "enterprise cloud" to "enterprise" plan across all products for consistency