feat: add provider metadata to registry

[FrozenArcher404]

Summary

• Adds a strict provider metadata schema with headquarters/name/slug and optional policy/status/terms URLs.
• Populates metadata for every current provider using the organization behind each base URL.
• Regenerates dist/providers.json so consumers receive metadata from the published artifact.

Validation

• bun run build
• bun run validate
• bun test