Save ticker and last decision to DB; add order suggestion UI; upsert stocks with execution details; ensure analysis saves ticker

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

prisma/schema.prisma

@@ -9,9 +9,12 @@ datasource db {
 }
 
 model Stock {
-  id        String   @id @default(cuid())
-  ticker    String   @unique
-  notes     String?
-  createdAt DateTime @default(now())
-  updatedAt DateTime @updatedAt
+  id               String   @id @default(cuid())
+  ticker           String   @unique
+  notes            String?
+  lastDecision     String?
+  lastExplanation  String?
+  lastExecutionPlan String?
+  createdAt        DateTime @default(now())
+  updatedAt        DateTime @updatedAt
 }