feat: support templateId in CreateExperienceProps for template-backed experiences [DX-982]

[Tyler Pina (tylerpina)]

DX-982

Summary

• Extends CreateExperienceProps to a discriminated union accepting either componentTypeId (component-type-backed) or templateId (template-backed), mirroring the upstream ExperienceConfigSchema
• Fixes the update REST adapter to extract templateId from sys.template.sys.id when updating a template-backed experience (previously only componentTypeId was handled)
• Updates the plain client create JSDoc example to document both creation paths

Test plan

• tsc --noEmit passes on feat/exo
• Unit test: create with templateId sends correct body
• Unit test: update with sys.template sends templateId (not componentTypeId) in body
• npm run test:unit — all 818 tests pass

Generated with Claude Code

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