Fix file_permissions tests to wait for file content instead of UI message

The tests were timing out on macOS because they waited for "Saved" to appear
on screen. Instead, wait for the actual file content to change on disk, which
is the real effect we're testing for.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: sinelaw

tests/e2e/file_permissions.rs

@@ -37,8 +37,15 @@ fn test_save_preserves_file_permissions() {
     harness
         .send_key(KeyCode::Char('s'), KeyModifiers::CONTROL)
         .unwrap();
-    // Wait for save to complete
-    harness.wait_for_screen_contains("Saved").unwrap();
+    // Wait for save to complete by checking file content changed
+    let file_path_clone = file_path.clone();
+    harness
+        .wait_until(move |_| {
+            std::fs::read_to_string(&file_path_clone)
+                .map(|s| s.starts_with("modified "))
+                .unwrap_or(false)
+        })
+        .unwrap();
 
     // Verify permissions are preserved
     let final_mode = std::fs::metadata(&file_path).unwrap().permissions().mode() & 0o777;
@@ -81,8 +88,15 @@ fn test_save_preserves_executable_permission() {
     harness
         .send_key(KeyCode::Char('s'), KeyModifiers::CONTROL)
         .unwrap();
-    // Wait for save to complete
-    harness.wait_for_screen_contains("Saved").unwrap();
+    // Wait for save to complete by checking file content changed
+    let file_path_clone = file_path.clone();
+    harness
+        .wait_until(move |_| {
+            std::fs::read_to_string(&file_path_clone)
+                .map(|s| s.contains("echo world"))
+                .unwrap_or(false)
+        })
+        .unwrap();
 
     // Verify executable permission is preserved
     let final_mode = std::fs::metadata(&file_path).unwrap().permissions().mode() & 0o777;
@@ -124,8 +138,15 @@ fn test_save_preserves_restricted_permissions() {
     harness
         .send_key(KeyCode::Char('s'), KeyModifiers::CONTROL)
         .unwrap();
-    // Wait for save to complete
-    harness.wait_for_screen_contains("Saved").unwrap();
+    // Wait for save to complete by checking file content changed
+    let file_path_clone = file_path.clone();
+    harness
+        .wait_until(move |_| {
+            std::fs::read_to_string(&file_path_clone)
+                .map(|s| s.starts_with("more "))
+                .unwrap_or(false)
+        })
+        .unwrap();
 
     // Verify restricted permissions are preserved
     let final_mode = std::fs::metadata(&file_path).unwrap().permissions().mode() & 0o777;