search: cache results

server/prisma/migrations/20260531000000_add_search_query_cache_key/migration.sql

@@ -0,0 +1,8 @@
+-- Add normalized search query lookup key for cache/reuse behavior.
+ALTER TABLE "Search" ADD COLUMN "queryNormalized" TEXT;
+
+UPDATE "Search"
+SET "queryNormalized" = lower(trim("query"))
+WHERE "query" IS NOT NULL AND trim("query") != '';
+
+CREATE INDEX "Search_queryNormalized_updatedAt_idx" ON "Search"("queryNormalized", "updatedAt");

server/prisma/schema.prisma

@@ -118,6 +118,7 @@ model Search {
 
   title String?
   query String?
+  queryNormalized String?
 
   source SearchSource @default(exa)
 
@@ -139,6 +140,7 @@ model Search {
   projectItems ProjectItem[]
 
   @@index([updatedAt])
+  @@index([queryNormalized, updatedAt])
   @@index([userId])
 }