Grounding pipeline and recipe-search settings API

recipes.Grounder ties search, fetch/extract, Rank, the photo cache and
normalize_recipe together. Ground(ctx, dishName, query) reuses a stored
source_url among the top candidates without fetching, otherwise tries the
ranked recipes best first and stores the photo, recipe, ingredients and
steps in one transaction, returning Grounded{recipe_id, photo_id, method,
minutes_total, difficulty, source_url, site_name} or a typed
*ErrUngroundable listing every reason. GroundURL grounds a pasted URL the
same way; GroundMany grounds items 3 at a time with per-item results.

PhotoCache is split into DownloadPhoto (fetch, decode, size check, no
writes) and CachePhoto(ctx, tx, photo), which records the row in the
caller's transaction; RemovePhotoFiles cleans up after a rollback.

Migration 0007 adds photo_id, method, difficulty and minutes_total to
recipes, and api_key_last4 to recipe_search_settings. SearXNG is now
called at recipe_search_settings.base_url.

GET/PATCH /api/v1/settings/recipe-search (Brave key sealed with
secretbox, only api_key_set and api_key_last4 returned) and POST
/api/v1/settings/recipe-search/test (searches "chicken tikka masala",
returns the count, 409 not_configured or 502 search_failed).

Maestro task 53afd59c-6c35-4af7-904c-6c167d1ad69d.

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

migrations/queries/recipes.sql

@@ -5,10 +5,12 @@
 -- DeleteRecipeIngredients/DeleteRecipeSteps then the Create queries.
 INSERT INTO recipes (
 	id, source_url, site_name, title, total_minutes, prep_minutes,
-	cook_minutes, yield, raw_jsonld, fetched_at, created_at, updated_at
+	cook_minutes, yield, raw_jsonld, photo_id, method, difficulty,
+	minutes_total, fetched_at, created_at, updated_at
 ) VALUES (
 	?, ?, ?, ?, ?, ?,
-	?, ?, ?, ?, ?, ?
+	?, ?, ?, ?, ?, ?,
+	?, ?, ?, ?
 )
 ON CONFLICT (source_url) DO UPDATE SET
 	site_name = excluded.site_name,
@@ -18,6 +20,10 @@ ON CONFLICT (source_url) DO UPDATE SET
 	cook_minutes = excluded.cook_minutes,
 	yield = excluded.yield,
 	raw_jsonld = excluded.raw_jsonld,
+	photo_id = excluded.photo_id,
+	method = excluded.method,
+	difficulty = excluded.difficulty,
+	minutes_total = excluded.minutes_total,
 	fetched_at = excluded.fetched_at,
 	updated_at = excluded.updated_at
 RETURNING *;