Gap: no UI for registration, email confirmation, or password reset

The backend serves registration, email confirmation and password reset, and the generated TypeScript client covers all of them — but the frontend demonstrates only login and logout. The contract-sync design put those screens out of scope deliberately (`docs/superpowers/specs/2026-09-04-contract-sync-reverse-urls-design.md`, *Explicitly out of scope*), which leaves a generated project with working endpoints nobody can reach without writing the pages first.

Open question is how far this goes: enough of a screen to prove the endpoint works, in the spirit of the login demo, or a complete account flow a developer would actually ship.

Came out of reviewing the deferred sections of the existing specs.

Read docs/superpowers/specs/2026-09-04-contract-sync-reverse-urls-design.md, especially the Explicitly out of scope section, then inspect the existing frontend login and logout demonstrations and the generated TypeScript client. First resolve whether the goal is endpoint-proving screens or a complete account flow; done means the chosen registration, email-confirmation, and password-reset scope is reachable through the frontend.

Written by the indexing model from the issue text.