Add Feedback domain module: public submission flow, admin CRUD, reporting (#7)

Co-authored-by: Patrick Müller <mail@pmueller.me>
Reviewed-on: #7
Co-authored-by: Patrick Mueller <patrick@mueller-patrick.tech>
Co-committed-by: Patrick Mueller <patrick@mueller-patrick.tech>

test/feedback/ratelimit.salt-guard.test.ts

@@ -0,0 +1,28 @@
+// Isolated from ratelimit.test.ts because it needs to control whether
+// FEEDBACK_IP_SALT is present at module-load time, which a real dotenv.config()
+// call would silently repopulate from the repo's .env file.
+jest.mock('dotenv', () => ({config: jest.fn()}));
+jest.mock('../../src/models/feedback/Feedback.db', () => ({
+	NachklangFeedbackDB: {getConnection: jest.fn()}
+}));
+
+describe('FEEDBACK_IP_SALT enforcement', () => {
+	const originalSalt = process.env.FEEDBACK_IP_SALT;
+
+	afterEach(() => {
+		process.env.FEEDBACK_IP_SALT = originalSalt;
+		jest.resetModules();
+	});
+
+	it('throws at import time when FEEDBACK_IP_SALT is unset, rather than silently hashing unsalted', () => {
+		jest.resetModules();
+		delete process.env.FEEDBACK_IP_SALT;
+		expect(() => require('../../src/models/feedback/feedback.ratelimit')).toThrow(/FEEDBACK_IP_SALT/);
+	});
+
+	it('does not throw when FEEDBACK_IP_SALT is set', () => {
+		jest.resetModules();
+		process.env.FEEDBACK_IP_SALT = 'a-real-salt';
+		expect(() => require('../../src/models/feedback/feedback.ratelimit')).not.toThrow();
+	});
+});