fix: cap Prisma pool during next build to stop deploy SSG timeouts

Next build workers were each opening up to DATABASE_POOL_SIZE connections and exhausting MySQL (pool active=0), hanging sitemap generation. Cap build pool to 5, fail connect faster, limit SSG concurrency, and make sitemap dynamic.

Co-authored-by: Cursor <[email protected]>

src/lib/prisma-pool.test.ts

@@ -0,0 +1,19 @@
+import { describe, expect, it } from "vitest";
+import { resolvePrismaConnectionLimit } from "./prisma-pool";
+
+describe("resolvePrismaConnectionLimit", () => {
+	it("caps the pool during production build phases", () => {
+		expect(resolvePrismaConnectionLimit(40, "phase-production-build")).toBe(5);
+		expect(
+			resolvePrismaConnectionLimit(40, "phase-production-compile"),
+		).toBe(5);
+		expect(resolvePrismaConnectionLimit(3, "phase-production-build")).toBe(3);
+	});
+
+	it("keeps the configured pool outside build", () => {
+		expect(resolvePrismaConnectionLimit(40, undefined)).toBe(40);
+		expect(resolvePrismaConnectionLimit(40, "phase-development-server")).toBe(
+			40,
+		);
+	});
+});