Add local authentication option (#37)

Co-authored-by: Shaun Campbell <shaun@campbellwireless.net>
Reviewed-on: #37
Co-authored-by: AI Agent <ai-agent@campbellwireless.net>
Co-committed-by: AI Agent <ai-agent@campbellwireless.net>

src/routes/login/page.server.test.ts

@@ -0,0 +1,37 @@
+import { beforeEach, describe, expect, it } from 'vitest';
+import { load } from './+page.server';
+
+beforeEach(() => {
+	process.env.AUTH_URL = 'https://example.com/auth';
+});
+
+describe('login page load', () => {
+	it('returns auth options when local auth is enabled', async () => {
+		process.env.LOCAL_AUTH_ENABLED = 'true';
+		const result = await load({
+			url: new URL('https://example.com/login')
+		} as Parameters<typeof load>[0]);
+
+		expect(result.signinUrl).toBe('https://example.com/auth/signin/synology');
+		expect(result.localSigninUrl).toBe('https://example.com/auth/signin/local');
+		expect(result.localAuthEnabled).toBe(true);
+	});
+
+	it('maps credentials errors to a generic message', async () => {
+		process.env.LOCAL_AUTH_ENABLED = 'true';
+		const result = await load({
+			url: new URL('https://example.com/login?error=CredentialsSignin')
+		} as Parameters<typeof load>[0]);
+
+		expect(result.error).toBe('Invalid credentials');
+	});
+
+	it('disables local auth in the response when disabled', async () => {
+		process.env.LOCAL_AUTH_ENABLED = 'false';
+		const result = await load({
+			url: new URL('https://example.com/login')
+		} as Parameters<typeof load>[0]);
+
+		expect(result.localAuthEnabled).toBe(false);
+	});
+});