API Builder V1: API defaults + endpoint templates

[nicdavidson]

Goal
Accelerate repetitive endpoint creation.

Scope

• API-level sticky defaults (source, output, limit)
• Endpoint templates: list, get-by-id, list+filter+sort

Acceptance Criteria

• New endpoint from template pre-fills source/route/shape defaults
• Standard endpoint created with 2-3 edits

[nicdavidson]

Delivered as part of API Builder V1 (adf-api-builder module). Closing tracking issue.