chore: harden deps, env validation, admin errors, and redis warnings

Align nodemailer with Auth.js peers, bump patch deps, validate env on deploy builds, add admin error boundary, and warn when Redis is missing in production.

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

src/lib/deploy-workflow-contract.test.ts

@@ -13,7 +13,8 @@ describe("production deploy workflow", () => {
 		expect(workflow).not.toMatch(/rm\s+-rf\s+\.next(?:\s|$)/);
 		expect(workflow).toContain("rm -rf .output dist .next/types .next/dev");
 		expect(workflow).toContain("pnpm install --frozen-lockfile");
-		expect(workflow).toContain("SKIP_ENV_VALIDATION=1");
+		// Production builds must validate env (AUTH_SECRET, DATABASE_URL, …).
+		expect(workflow).not.toContain("SKIP_ENV_VALIDATION=1");
 	});
 
 	it("reclaims ownership before git reset so www-data files can be overwritten", () => {