feat: add stock database with prisma for portfolio persistence

- Initialize Prisma with SQLite and Stock model
- Create database service layer with singleton client
- Add API routes for stock CRUD operations
- Integrate database with analyze page to persist ticker entries
- Add Playwright tests for stock database functionality

app/lib/db.server.ts

@@ -0,0 +1,15 @@
+import { PrismaClient } from "@prisma/client";
+
+declare global {
+  var prisma: PrismaClient | undefined;
+}
+
+const prismaClientSingleton = () => {
+  return new PrismaClient();
+};
+
+export const db = global.prisma || prismaClientSingleton();
+
+if (process.env.NODE_ENV !== "production") {
+  global.prisma = db;
+}

app/lib/openrouter.ts

@@ -9,20 +9,21 @@ type OpenRouterConfig = {
 };
 
 export class OpenRouterClient {
-  private apiKey: string;
-  private baseURL: string;
-  private defaultModel: string;
-  private freeModels = [
-    "google/gemini-2.0-flash-exp:free",
-    "deepseek/deepseek-chat:free",
-    "meta/llama-3.3-70b-instruct:free",
-  ];
-  private providers = ["openai", "google", "anthropic", "deepseek", "meta", "xai"];
+   private apiKey: string;
+   private baseURL: string;
+   private defaultModel: string;
+   private freeModels = [
+     "openai/gpt-oss-120b:free",
+     "openrouter/free",
+     "deepseek/deepseek-chat:free",
+     "meta/llama-3.3-70b-instruct:free",
+   ];
+   private providers = ["openai", "google", "anthropic", "deepseek", "meta", "xai"];
 
   constructor(apiKey: string, config?: OpenRouterConfig) {
     this.apiKey = apiKey;
     this.baseURL = config?.baseURL ?? "https://openrouter.ai/api/v1";
-    this.defaultModel = config?.defaultModel ?? "google/gemini-2.0-flash-exp:free";
+    this.defaultModel = config?.defaultModel ?? "openai/gpt-oss-120b:free";
   }
 
   getFreeModels(): string[] {