Add Prisma migration for NewsArticle model

The previous commit used `prisma db push` which doesn't create migration
files. Railway runs `prisma migrate deploy` on startup, which requires a
migration file in prisma/migrations/ to apply schema changes.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

prisma/migrations/20260301000000_add_news_article/migration.sql

@@ -0,0 +1,25 @@
+-- CreateTable
+CREATE TABLE "NewsArticle" (
+    "id" TEXT NOT NULL,
+    "symbol" TEXT NOT NULL,
+    "headline" TEXT NOT NULL,
+    "summary" TEXT NOT NULL,
+    "source" TEXT NOT NULL,
+    "url" TEXT NOT NULL,
+    "imageUrl" TEXT,
+    "publishedAt" TIMESTAMP(3) NOT NULL,
+    "finnhubId" INTEGER NOT NULL,
+    "createdAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updatedAt" TIMESTAMP(3) NOT NULL,
+
+    CONSTRAINT "NewsArticle_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateIndex
+CREATE UNIQUE INDEX "NewsArticle_finnhubId_key" ON "NewsArticle"("finnhubId");
+
+-- CreateIndex
+CREATE INDEX "NewsArticle_symbol_idx" ON "NewsArticle"("symbol");
+
+-- CreateIndex
+CREATE INDEX "NewsArticle_publishedAt_idx" ON "NewsArticle"("publishedAt");