feat: print name in output filename; export panel trim; queue template fix

- Output filename now includes the print: <garment>_<print>.<ext>, e.g.
  1_TY030.png (folder grouping unchanged) (§17.12).
- Hide the single-export button (export via the queue) and remove the
  orphaned static export hint label (§17.13).
- Fix: selecting a non-fine-tuned queue item now lays the print out per the
  selected template (apply_current) instead of load_print's centred default;
  still guarded by _loading_queue_item so it isn't marked 已微调 (§17.14).

Docs: PRD 6.6/6.8/9, UI design 7.6/7.7/10/12.4, tasks.md 17.12–17.14.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/main_window.py

@@ -325,11 +325,8 @@ class MainWindow(QMainWindow):
             self.image_canvas.load_print(print_path)
             self.export_panel.set_garment(garment_path)
             self.export_panel.set_print(print_path)
-            # If the item already has a fine-tuned transform, restore it
-            if item.transform:
-                self.image_canvas.set_transform(item.transform)
-                self.transform_panel.set_transform(item.transform)
-            # Keep template panel garment and print size in sync
+            # Keep template panel garment and print size in sync first, so
+            # apply_current() below can compute the template layout.
             try:
                 from PIL import Image as _PilImage
                 with _PilImage.open(garment_path) as img:
@@ -338,6 +335,13 @@ class MainWindow(QMainWindow):
                     self.template_panel.set_print_size(img.width, img.height)
             except Exception:
                 pass
+            # Fine-tuned item: restore its own transform. Otherwise lay the print
+            # out per the selected template instead of load_print's default.
+            if item.transform:
+                self.image_canvas.set_transform(item.transform)
+                self.transform_panel.set_transform(item.transform)
+            else:
+                self.template_panel.apply_current()
         finally:
             self._loading_queue_item = False
         self._update_reset_availability()