Update aiusechat read_dir tests for typed entry output (#3007)

`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

```go
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
    }
}
```

<!-- START COPILOT CODING AGENT TIPS -->
---

✨ Let Copilot coding agent [set things up for
you](https://github.com/wavetermdev/waveterm/issues/new?title=✨+Set+up+Copilot+instructions&body=Configure%20instructions%20for%20this%20repository%20as%20documented%20in%20%5BBest%20practices%20for%20Copilot%20coding%20agent%20in%20your%20repository%5D%28https://gh.io/copilot-coding-agent-tips%29%2E%0A%0A%3COnboard%20this%20repo%3E&assignees=copilot)
— coding agent works faster and does higher quality work when set up for
your repo.

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: sawka <2722291+sawka@users.noreply.github.com>

Author: Copilot

pkg/aiusechat/tools_readdir_test.go

@@ -11,6 +11,7 @@ import (
 	"testing"
 
 	"github.com/wavetermdev/waveterm/pkg/aiusechat/uctypes"
+	"github.com/wavetermdev/waveterm/pkg/util/fileutil"
 )
 
 func TestReadDirCallback(t *testing.T) {
@@ -64,16 +65,16 @@ func TestReadDirCallback(t *testing.T) {
 		t.Errorf("Expected 3 entries, got %d", entryCount)
 	}
 
-	entries, ok := resultMap["entries"].([]map[string]any)
+	entries, ok := resultMap["entries"].([]fileutil.DirEntryOut)
 	if !ok {
-		t.Fatalf("entries is not a slice of maps")
+		t.Fatalf("entries is not a slice of DirEntryOut")
 	}
 
 	// Check that we have the expected entries
 	foundFiles := 0
 	foundDirs := 0
 	for _, entry := range entries {
-		if entry["is_dir"].(bool) {
+		if entry.Dir {
 			foundDirs++
 		} else {
 			foundFiles++
@@ -208,12 +209,15 @@ func TestReadDirSortBeforeTruncate(t *testing.T) {
 	}
 
 	resultMap := result.(map[string]any)
-	entries := resultMap["entries"].([]map[string]any)
+	entries, ok := resultMap["entries"].([]fileutil.DirEntryOut)
+	if !ok {
+		t.Fatalf("entries is not a slice of DirEntryOut")
+	}
 
 	// Count directories in the result
 	dirCount := 0
 	for _, entry := range entries {
-		if entry["is_dir"].(bool) {
+		if entry.Dir {
 			dirCount++
 		}
 	}
@@ -225,7 +229,7 @@ func TestReadDirSortBeforeTruncate(t *testing.T) {
 
 	// First 3 entries should be directories
 	for i := 0; i < 3; i++ {
-		if !entries[i]["is_dir"].(bool) {
+		if !entries[i].Dir {
 			t.Errorf("Expected entry %d to be a directory, but it was a file", i)
 		}
 	}