feat: add Docker support with demo mode and database reset functionality

tests/unit.test.ts

@@ -8,6 +8,22 @@ import { localClock, localInstant, pickupState } from "../src/lib/time";
 import { childSchema, correctionSchema, daySchema, overrideSchema, aloneRulesSchema, contactSchema, slotSchema, applicationSchema } from "../src/lib/validation";
 import { hashPassword, verifyPassword } from "../src/lib/password";
 import { chooseWinners, invitationHash, newInvitation } from "../src/lib/admissions";
+import { demoLogin, isDemoDatabase } from "../src/lib/demo";
+
+test("Demozugang nur bei explizitem Modus; Container-Reset nur fuer isolierte Demo-Datenbank", () => {
+  const normal = { NODE_ENV: "test" } as const;
+  assert.equal(demoLogin(normal), undefined);
+  assert.equal(demoLogin({ ...normal, DEMO_MODE: "false" }), undefined);
+  assert.equal(demoLogin({ ...normal, DEMO_MODE: "TRUE" }), undefined);
+  const demo = { ...normal, DEMO_MODE: "true", DEMO_RESET_ON_START: "true" };
+  assert.deepEqual(demoLogin(demo), { email: "demo@kibu.local", password: "KIBU-Demo-2026!" });
+  const target = new URL("postgresql://demo-db/kibu_demo");
+  assert.equal(isDemoDatabase(target, demo), true);
+  assert.equal(isDemoDatabase(target, normal), false);
+  assert.equal(isDemoDatabase(target, { ...demo, DEMO_RESET_ON_START: "false" }), false);
+  assert.equal(isDemoDatabase(new URL("postgresql://demo-db/kibu"), demo), false);
+  assert.equal(isDemoDatabase(new URL("postgresql://production/kibu_demo"), demo), false);
+});
 
 test("Abholfenster: genau jetzt und bis einschließlich 15 Minuten, überfällig erst davor", () => {
   assert.equal(pickupState(null, "14:00"), "none");