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/csv.service.test.ts

@@ -0,0 +1,58 @@
+import {escapeCsvField} from '../../src/models/feedback/admin/csv.service';
+import {formatDatetime} from '../../src/models/feedback/feedback.dates';
+
+describe('escapeCsvField', () => {
+	it('passes plain text through unchanged', () => {
+		expect(escapeCsvField('Abendlied')).toBe('Abendlied');
+	});
+
+	it('converts null/undefined to an empty string', () => {
+		expect(escapeCsvField(null)).toBe('');
+		expect(escapeCsvField(undefined)).toBe('');
+	});
+
+	it('converts numbers to strings', () => {
+		expect(escapeCsvField(5)).toBe('5');
+	});
+
+	it('quotes and doubles internal quotes (RFC 4180)', () => {
+		expect(escapeCsvField('Sie sagte "Danke"')).toBe('"Sie sagte ""Danke"""');
+	});
+
+	it('quotes a field containing the ; separator', () => {
+		expect(escapeCsvField('Rheinberger; Bach')).toBe('"Rheinberger; Bach"');
+	});
+
+	it('strips embedded newlines instead of breaking the row', () => {
+		expect(escapeCsvField('Zeile 1\r\nZeile 2')).toBe('Zeile 1 Zeile 2');
+		expect(escapeCsvField('Zeile 1\nZeile 2')).toBe('Zeile 1 Zeile 2');
+	});
+
+	it('prefixes formula-injection characters with an apostrophe', () => {
+		expect(escapeCsvField('=1+1')).toBe("'=1+1");
+		expect(escapeCsvField('+SUM(A1)')).toBe("'+SUM(A1)");
+		expect(escapeCsvField('-2')).toBe("'-2");
+		expect(escapeCsvField('@example')).toBe("'@example");
+	});
+
+	it('does not treat a mid-string = as formula injection', () => {
+		expect(escapeCsvField('x = y')).toBe('x = y');
+	});
+});
+
+describe('formatDatetime', () => {
+	it('formats a Date as YYYY-MM-DD HH:mm:ss, not the verbose Date.toString()', () => {
+		const d = new Date(2026, 7, 2, 21, 59, 21); // month is 0-indexed: August
+		expect(formatDatetime(d)).toBe('2026-08-02 21:59:21');
+		expect(formatDatetime(d)).not.toContain('GMT');
+	});
+
+	it('pads single-digit components', () => {
+		const d = new Date(2026, 0, 5, 3, 4, 5);
+		expect(formatDatetime(d)).toBe('2026-01-05 03:04:05');
+	});
+
+	it('returns an empty string for null', () => {
+		expect(formatDatetime(null)).toBe('');
+	});
+});