refactor(views): ON CONFLICT DO UPDATE statt INSERT OR REPLACE

Code-Review-Finding zu commit 6c8de6f: INSERT OR REPLACE ist intern
DELETE+INSERT, das wuerde eventuelle FK-Children kuenftig stillschweigend
mitloeschen. ON CONFLICT DO UPDATE bumpt nur das Timestamp-Feld und
matcht den Stil der anderen Repos (shopping/repository.ts:43).

Migration-Dateiname zu recipe_view (singular) angeglichen, matcht
jetzt den Tabellennamen aus 543008b.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/lib/server/recipes/views.ts

@@ -5,12 +5,14 @@ export function recordView(
   profileId: number,
   recipeId: number
 ): void {
-  // INSERT OR REPLACE re-fires the DEFAULT (CURRENT_TIMESTAMP) on conflict,
-  // so subsequent views of the same recipe by the same profile bump the
-  // timestamp without breaking the composite PK.
+  // ON CONFLICT DO UPDATE bumps only the timestamp field — avoids the
+  // DELETE+INSERT that INSERT OR REPLACE performs under the hood, which would
+  // silently cascade-delete any future FK-referencing children.
   db.prepare(
-    `INSERT OR REPLACE INTO recipe_view (profile_id, recipe_id)
-     VALUES (?, ?)`
+    `INSERT INTO recipe_view (profile_id, recipe_id)
+     VALUES (?, ?)
+     ON CONFLICT(profile_id, recipe_id) DO UPDATE
+       SET last_viewed_at = CURRENT_TIMESTAMP`
   ).run(profileId, recipeId);
 }