v1.5.0

Changed

• Bumped the django-admin-rest-api floor to ^1.7.0, which replaces the
  legacy-iframe path with server-rendered html-fragment form-spec payloads
  for ModelAdmins that render a custom template
  (#84).

Added

• custom-template discriminator for change_form_template admins
  (#84).
  When rest-api's shared form-spec resolver renders a custom template (a
  declared change_form_template / add_form_template, or a request-driven
  change_view override) it returns renderer: "html-fragment" — opaque HTML
  an MCP client can't introspect or drive. admin.form_spec now renames that
  single upstream signal to a clear non-driveable discriminator:
  { "renderer": "custom-template", "reason": "ModelAdmin override: change_form_template", "legacy_url": …, "spa_url": …, "machine_driveable": false }. legacy_url is
  the upstream submit_url; spa_url is derived by reusing rest-api's
  map_redirect_to_spa (the /admin/ → SPA_URL_PREFIX swap), so detection is
  never duplicated here. admin.form_submit against such a form now refuses
  to submit — it does not fabricate field values or forward a POST — and returns
  { "ok": false, "reason": "custom-template", "message": "… not programmatically driveable …" }
  (isError: true, status 422). The pre-1.7.0 legacy-iframe branch is
  dropped: MCP clients never iframed anything, so it was never meaningful here.

Documentation

• tools-reference.md: documented admin.form_spec / admin.form_submit
  (previously undocumented) and the custom-template discriminator + refusal.
• api-contract.md §4.4: documented the one narrow exception to the
  pure-pass-through contract (the html-fragment → custom-template rename).
• threat-model.md §3: added the "agent fabricating field values for an
  opaque custom-template form" row (mitigated by the discriminator + refusal).