Update aiusechat read_dir tests for typed entry output

[Copilot]

pkg/aiusechat/tools_readdir_test.go was still asserting the old entries payload shape after read_dir moved to returning typed directory entries. This caused the pkg/aiusechat test failures even though the tool behavior itself was already correct.

• Align test expectations with current callback output

  • Update TestReadDirCallback to treat entries as []fileutil.DirEntryOut
  • Assert directory/file classification via the Dir field instead of map lookups

• Fix truncation/sorting coverage

  • Update TestReadDirSortBeforeTruncate to validate the typed slice returned by readDirCallback
  • Preserve the existing intent of the test: directories should still be sorted ahead of files before truncation

• Keep scope limited to stale tests

  • No changes to read_dir implementation or output contract
  • Only the broken test assumptions were corrected

entries, ok := resultMap["entries"].([]fileutil.DirEntryOut)
if !ok {
    t.Fatalf("entries is not a slice of DirEntryOut")
}

for _, entry := range entries {
    if entry.Dir {
        // directory assertions
    }
}

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