Record site-name provenance instead of inferring it from the name's shape

Recipe extraction no longer falls back to the URL's host: a stored
recipes.site_name is now always a name the page gave (publisher or
og:site_name), and null when it named none. dinners.SourceOf is the one
documented rule for every fetched recipe's source: the page's name is
shown as it stands; otherwise the site is named by the link's host only
when the link itself is shown as free of secrets, else null. The recipe
detail, idea results and the recipe-candidate offer endpoint all apply
it; candidates no longer carry an extraction-time hostname fallback, so
their site_name is nullable (frontend updated to match).

Migration 0020 clears host-shaped site names (dotted host names, IP
addresses) stored before the change, in recipes and in legacy idea job
results, so already-stored rows read under the same rule.

Maestro 966066e3-0e25-4b8b-9bb0-0694c47c9106

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

web/src/dinners/api.ts

@@ -54,7 +54,9 @@ export type RecipeFix = { candidate_id: string } | { recipe_url: string } | { ma
 export type RecipeCandidate = {
   candidate_id: string
   title: string
-  site_name: string
+  // site_name is null when the server cannot name the page's site without
+  // leaking its link (dinners.SourceOf).
+  site_name: string | null
   photo_id: string | undefined
   minutes: number | null
 }
@@ -130,7 +132,7 @@ function parseCandidate(where: string, body: unknown): RecipeCandidate {
     !isRecord(body) ||
     typeof body.candidate_id !== 'string' ||
     typeof body.title !== 'string' ||
-    typeof body.site_name !== 'string'
+    (body.site_name !== null && typeof body.site_name !== 'string')
   ) {
     throw new Error(`${where}: response is not a recipe candidate`)
   }