fix: add FTS5 sync triggers so recipe inserts are indexed immediately

Migration 015 did a one-time rebuild of recipes_fts at creation time but
omitted triggers, so rows inserted after that point were invisible to MATCH
queries. Adds AFTER INSERT/UPDATE/DELETE triggers to 015 (fresh DBs / tests)
and migration 016 to backfill them on existing databases.

Fixes 3 failing tests: test_search_recipes_by_ingredient_names,
test_level1_returns_ranked_suggestions, test_level2_returns_swap_candidates.

app/db/migrations/015_recipe_fts.sql

@@ -14,3 +14,25 @@ CREATE VIRTUAL TABLE IF NOT EXISTS recipes_fts USING fts5(
 );
 
 INSERT INTO recipes_fts(recipes_fts) VALUES('rebuild');
+
+-- Triggers to keep the FTS index in sync with the recipes table.
+-- Without these, rows inserted after the initial rebuild are invisible to FTS queries.
+CREATE TRIGGER IF NOT EXISTS recipes_fts_ai
+  AFTER INSERT ON recipes BEGIN
+    INSERT INTO recipes_fts(rowid, ingredient_names)
+    VALUES (new.id, new.ingredient_names);
+END;
+
+CREATE TRIGGER IF NOT EXISTS recipes_fts_ad
+  AFTER DELETE ON recipes BEGIN
+    INSERT INTO recipes_fts(recipes_fts, rowid, ingredient_names)
+    VALUES ('delete', old.id, old.ingredient_names);
+END;
+
+CREATE TRIGGER IF NOT EXISTS recipes_fts_au
+  AFTER UPDATE ON recipes BEGIN
+    INSERT INTO recipes_fts(recipes_fts, rowid, ingredient_names)
+    VALUES ('delete', old.id, old.ingredient_names);
+    INSERT INTO recipes_fts(rowid, ingredient_names)
+    VALUES (new.id, new.ingredient_names);
+END;

app/db/migrations/016_recipe_fts_triggers.sql

@@ -0,0 +1,27 @@
+-- Migration 016: Add FTS5 sync triggers for the recipes_fts content table.
+--
+-- Migration 015 created recipes_fts and did a one-time rebuild, but omitted
+-- triggers. Without them, INSERT/UPDATE/DELETE on recipes does not update the
+-- FTS index, so new rows are invisible to MATCH queries.
+--
+-- CREATE TRIGGER IF NOT EXISTS is idempotent — safe to re-run.
+
+CREATE TRIGGER IF NOT EXISTS recipes_fts_ai
+  AFTER INSERT ON recipes BEGIN
+    INSERT INTO recipes_fts(rowid, ingredient_names)
+    VALUES (new.id, new.ingredient_names);
+END;
+
+CREATE TRIGGER IF NOT EXISTS recipes_fts_ad
+  AFTER DELETE ON recipes BEGIN
+    INSERT INTO recipes_fts(recipes_fts, rowid, ingredient_names)
+    VALUES ('delete', old.id, old.ingredient_names);
+END;
+
+CREATE TRIGGER IF NOT EXISTS recipes_fts_au
+  AFTER UPDATE ON recipes BEGIN
+    INSERT INTO recipes_fts(recipes_fts, rowid, ingredient_names)
+    VALUES ('delete', old.id, old.ingredient_names);
+    INSERT INTO recipes_fts(rowid, ingredient_names)
+    VALUES (new.id, new.ingredient_names);
+END;