fix: support reusable templates in remote CLI

[andrei-hasna]

Summary:

• Add authenticated /v1/templates create, list, read, and delete endpoints for self-hosted Todos.
• Preserve ordered checklist steps in the remote Postgres adapter.
• Route templates create/list and template-import through cloud HTTP with no SQLite fallback.

Validation passed:

• focused storage, v1, remote-entrypoint, cloud-list-filter, and OpenAPI test suites
• typecheck
• server build
• staged and commit-range gitleaks scans

No deployment or production data mutation was performed.