refactor(host): browse flow off the ./client surface (export discipline)

BrowseDirectoryFlow and its injected face move to the package-internal
src/client/flow.ts, mirroring -native: ./client exports only the Loader
surface and the same-package spec imports the internal module directly.

packages/host/directory-picker-browse/src/client/flow.ts

@@ -0,0 +1,43 @@
+/**
+ * The browse picking occupant (package-internal; the `./client` surface
+ * exposes only the Loader exports). Same-package tests exercise it directly
+ * through this module.
+ */
+import { createElement } from 'react'
+import type { ReactElement } from 'react'
+import type { DirectoryListing } from '@deepseek-ai/dsh-client-runtime/client'
+import type { Translate } from '@deepseek-ai/dsh-client-locale/client'
+// Type-only: the owner contract of the directory-flow holes.
+import type { DirectoryFlowOwnerProps } from '@deepseek-ai/dsh-client-ui-workspace/client'
+import { DirectoryBrowser } from './DirectoryBrowser.tsx'
+
+/** Injected face: the browse wire calls and copy the dialog drives (bound in apply's closure). */
+export interface BrowseFlowInjected {
+  /** List one directory level (absent path = the Host home directory). */
+  listDirectory: (path?: string) => Promise<DirectoryListing>
+  /** Create one child directory under an existing parent. */
+  createDirectory: (path: string, name: string) => Promise<string>
+  /** Localized dialog copy (this package's namespace). */
+  t: Translate
+}
+
+/**
+ * Flow occupant: adapts the hole's owner conversation onto the browser
+ * dialog — a confirmed directory is the picked path, dismissal is the
+ * cancellation. Browse failures (unreadable targets, create conflicts) stay
+ * inside the dialog's own alert surfaces, so the owner's `onError` arm is
+ * never driven by this occupant.
+ * @param props - owner conversation plus the injected browse face.
+ * @returns the dialog element (renders nothing while closed).
+ */
+export function BrowseDirectoryFlow(props: DirectoryFlowOwnerProps & BrowseFlowInjected): ReactElement {
+  return createElement(DirectoryBrowser, {
+    open: props.open,
+    busy: props.busy,
+    listDirectory: props.listDirectory,
+    createDirectory: props.createDirectory,
+    t: props.t,
+    onOpen: props.onPicked,
+    onClose: props.onCancel,
+  })
+}