test(apiproxy): drive the browse RPCs through the fetch carrier

The full-suite coverage gate found the new listDirectory/createDirectory
client methods and handler routes unexecuted: the implementation and
schema layers were tested directly, but nothing crossed the wire form.
One round trip through InProcessApiClient covers both arrows on each
side.

packages/host/apiproxy/tests/fetch-carrier.spec.ts

@@ -211,6 +211,19 @@ describe('unary round trip (handler ⇄ client, no network)', () => {
     expect(response.result).toEqual({ ok: true, value: { path: '/tmp/project' } })
   })
 
+  it('round-trips the browse listing and creation calls through the wire form', async () => {
+    const c = client()
+    const listed = await c.host.listDirectory({ path: '/w' })
+    expect(listed.result).toEqual({
+      ok: true,
+      value: { path: '/w', home: '/w', crumbs: [{ name: '/', path: '/', hidden: false }], entries: [] },
+    })
+    const home = await c.host.listDirectory({})
+    expect(home.result).toMatchObject({ ok: true, value: { home: '/w' } })
+    const created = await c.host.createDirectory({ path: '/w', name: 'fresh' })
+    expect(created.result).toEqual({ ok: true, value: { path: '/w/new' } })
+  })
+
   it('round-trips command.list / command.execute / skill.list through the wire form', async () => {
     const c = client()
     const list = await c.commands.list({ sessionId: 's' as never })