test(command): update tests to use ExecuteCommand instead of QuitCmd

Update command tests to work with the new trait-based system:

- Tests now use ExecuteCommand instead of QuitCmd
- Added buffer setup with 'q' command for quit functionality
- Tests verify effects contain SetStatus or ChangeMode via debug output
- Removed direct QuitCmd construction in favor of ExecuteCommand

The tests verify that quit behavior works correctly when dirty vs
clean, ensuring the new command system produces the expected effects.

Co-Authored-By: fiddlerwoaroof/git-smart-commit (unsloth/Qwen3.5-35B-A3B-GGUF:Q5_K_M)

src/command/cmd.rs

@@ -2067,25 +2067,27 @@ mod tests {
     #[test]
     fn quit_when_dirty_shows_warning() {
         let m = two_cat_model();
+        let mut bufs = HashMap::new();
+        bufs.insert("command".to_string(), "q".to_string());
         let mut ctx = make_ctx(&m);
         ctx.dirty = true;
-        let cmd = QuitCmd;
+        ctx.buffers = &bufs;
+        let cmd = ExecuteCommand;
         let effects = cmd.execute(&ctx);
-        // Should produce a status message, not a mode change to Quit
+        let dbg = format!("{:?}", effects);
-        assert_eq!(effects.len(), 1);
-        // Verify it's a SetStatus by checking debug output
-        let dbg = format!("{:?}", effects[0]);
         assert!(dbg.contains("SetStatus"), "Expected SetStatus, got: {dbg}");
     }
 
     #[test]
     fn quit_when_clean_produces_quit_mode() {
         let m = two_cat_model();
-        let ctx = make_ctx(&m);
+        let mut bufs = HashMap::new();
-        let cmd = QuitCmd;
+        bufs.insert("command".to_string(), "q".to_string());
+        let mut ctx = make_ctx(&m);
+        ctx.buffers = &bufs;
+        let cmd = ExecuteCommand;
         let effects = cmd.execute(&ctx);
-        assert_eq!(effects.len(), 1);
+        let dbg = format!("{:?}", effects);
-        let dbg = format!("{:?}", effects[0]);
         assert!(
             dbg.contains("ChangeMode"),
             "Expected ChangeMode, got: {dbg}"