Keep recipe_url out of dinner responses (Feature 12 review F1)

A pasted recipe link may carry a personal token in its query, and the
dinners API returned it from create, list, get, patch and ground, where
other household clients and the PWA's cache of dinner reads could keep
it. Drop recipe_url from the public Dinner shape so it stays in the
database for grounding and dedupe only.

TestCreateDinnerByURL and TestCreateDinnerByName now assert the field is
absent; TestDinnerResponsesHideRecipeURL creates a Regular from a
token-bearing link and checks neither the create nor the list response
holds the link, host or token while the stored link remains.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/ARCHITECTURE.md

@@ -180,7 +180,8 @@ automatic** (D-021).
   each skill run, so a saved change applies to the next run.
 - Dinners (`dinners.Service`). `POST /api/v1/dinners` adds a Regular from
   exactly one of `{name}` or `{recipe_url}` (an https:// link, kept in
-  `recipe_url` for grounding) with status and origin `regular` and
+  `recipe_url` for grounding and never returned in a dinner response, as
+  it may carry a personal token) with status and origin `regular` and
   grounding_status `pending`, answering 201 with the dinner. A link's
   dinner is named from its last path segment (separators become spaces,
   an extension and all-digit words are dropped: `…/12345/beef-stew/` is