fix(host): bound listDirectory levels at a configurable maxEntries

One list call now materializes at most maxEntries child rows (config,
default 1000 - GitHub's web-UI directory-listing bound). Candidates sort
before probing so a cut level keeps the name-sorted head and symlink
probing stops with the bound, and DirectoryListing carries a required
truncated flag on the seam and the wire so clients can state
incompleteness instead of silently missing tail entries.

packages/client/connection/src/client/fixture.ts

@@ -880,6 +880,8 @@ export function createFixtureApi(options: FixtureOptions = {}): ApiProxy {
           crumbs: crumbsOf(target),
           entries: [...children].sort((a, b) => a.localeCompare(b))
             .map(name => ({ name, path: target === '/' ? `/${name}` : `${target}/${name}`, hidden: name.startsWith('.') })),
+          // The fixture tree is tiny; no level ever reaches a backend bound.
+          truncated: false,
         })
       },
       createDirectory: (request) => {