Show sent/received cookie counts in Cookies tab

- Add getCookieCounts function to parse cookie headers and count
  individual cookies (not just headers)
- Deduplicates by cookie name using Sets
- Display as sent/received format like Headers tab
- Add showZero to CountBadge so 0/3 displays properly
- Add tests for getCookieCounts

src-web/lib/model_util.test.ts

@@ -0,0 +1,93 @@
+import type { HttpResponseEvent } from '@yaakapp-internal/models';
+import { describe, expect, test } from 'vitest';
+import { getCookieCounts } from './model_util';
+
+function makeEvent(
+  type: string,
+  name: string,
+  value: string,
+): HttpResponseEvent {
+  return {
+    id: 'test',
+    model: 'http_response_event',
+    responseId: 'resp',
+    createdAt: Date.now(),
+    event: { type, name, value } as HttpResponseEvent['event'],
+  };
+}
+
+describe('getCookieCounts', () => {
+  test('returns zeros for undefined events', () => {
+    expect(getCookieCounts(undefined)).toEqual({ sent: 0, received: 0 });
+  });
+
+  test('returns zeros for empty events', () => {
+    expect(getCookieCounts([])).toEqual({ sent: 0, received: 0 });
+  });
+
+  test('counts single sent cookie', () => {
+    const events = [makeEvent('header_up', 'Cookie', 'session=abc123')];
+    expect(getCookieCounts(events)).toEqual({ sent: 1, received: 0 });
+  });
+
+  test('counts multiple sent cookies in one header', () => {
+    const events = [makeEvent('header_up', 'Cookie', 'a=1; b=2; c=3')];
+    expect(getCookieCounts(events)).toEqual({ sent: 3, received: 0 });
+  });
+
+  test('counts single received cookie', () => {
+    const events = [makeEvent('header_down', 'Set-Cookie', 'session=abc123; Path=/')];
+    expect(getCookieCounts(events)).toEqual({ sent: 0, received: 1 });
+  });
+
+  test('counts multiple received cookies from multiple headers', () => {
+    const events = [
+      makeEvent('header_down', 'Set-Cookie', 'a=1; Path=/'),
+      makeEvent('header_down', 'Set-Cookie', 'b=2; HttpOnly'),
+      makeEvent('header_down', 'Set-Cookie', 'c=3; Secure'),
+    ];
+    expect(getCookieCounts(events)).toEqual({ sent: 0, received: 3 });
+  });
+
+  test('deduplicates sent cookies by name', () => {
+    const events = [
+      makeEvent('header_up', 'Cookie', 'session=old'),
+      makeEvent('header_up', 'Cookie', 'session=new'),
+    ];
+    expect(getCookieCounts(events)).toEqual({ sent: 1, received: 0 });
+  });
+
+  test('deduplicates received cookies by name', () => {
+    const events = [
+      makeEvent('header_down', 'Set-Cookie', 'token=abc; Path=/'),
+      makeEvent('header_down', 'Set-Cookie', 'token=xyz; Path=/'),
+    ];
+    expect(getCookieCounts(events)).toEqual({ sent: 0, received: 1 });
+  });
+
+  test('counts both sent and received cookies', () => {
+    const events = [
+      makeEvent('header_up', 'Cookie', 'a=1; b=2; c=3'),
+      makeEvent('header_down', 'Set-Cookie', 'x=10; Path=/'),
+      makeEvent('header_down', 'Set-Cookie', 'y=20; Path=/'),
+      makeEvent('header_down', 'Set-Cookie', 'z=30; Path=/'),
+    ];
+    expect(getCookieCounts(events)).toEqual({ sent: 3, received: 3 });
+  });
+
+  test('ignores non-cookie headers', () => {
+    const events = [
+      makeEvent('header_up', 'Content-Type', 'application/json'),
+      makeEvent('header_down', 'Content-Length', '123'),
+    ];
+    expect(getCookieCounts(events)).toEqual({ sent: 0, received: 0 });
+  });
+
+  test('handles case-insensitive header names', () => {
+    const events = [
+      makeEvent('header_up', 'COOKIE', 'a=1'),
+      makeEvent('header_down', 'SET-COOKIE', 'b=2; Path=/'),
+    ];
+    expect(getCookieCounts(events)).toEqual({ sent: 1, received: 1 });
+  });
+});