V2.1.0 — Formats personnalises + reperes de coupe

- Formats personnalises dans tous les menus deroulants de format :
  - "Personnalise..." : saisie libre largeur x hauteur en mm
  - "Ajouter un format..." : sauvegarder un format custom (persistant)
  - Formats custom affiches dans le dropdown avec separateur
- Reperes de coupe (Annotations > Reperes de coupe) :
  - Longueur, distance du bord, epaisseur configurables
  - Couleur : noir, gris, CMYK
  - Reperes de centrage optionnels
  - Appliquer a : toutes, paires, impaires, page courante
  - Enlever les reperes de coupe (menu)
- Step & Repeat : ajout des marges (haut, bas, gauche, droite)
- Tous les dialogues de format migres vers format_combo

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/dialogs/nup_dialog.py

@@ -2,8 +2,10 @@
 
 from PyQt6.QtWidgets import (QDialog, QVBoxLayout, QHBoxLayout, QLabel,
                               QComboBox, QGroupBox, QSpinBox, QCheckBox,
-                              QDialogButtonBox, QDoubleSpinBox, QFileDialog)
-from app.engine.pdf_utils import PAGE_SIZES, mm_to_pt
+                              QDialogButtonBox, QDoubleSpinBox, QFileDialog,
+                              QPushButton)
+from app.engine.pdf_utils import mm_to_pt
+from app.dialogs.format_combo import populate_format_combo, get_selected_size, handle_format_selection
 
 
 class NupDialog(QDialog):
@@ -17,7 +19,6 @@ class NupDialog(QDialog):
     def _setup_ui(self):
         layout = QVBoxLayout(self)
 
-        # Grille
         grp_grid = QGroupBox("Disposition")
         gl = QHBoxLayout(grp_grid)
         gl.addWidget(QLabel("Colonnes :"))
@@ -32,18 +33,15 @@ class NupDialog(QDialog):
         gl.addWidget(self.spin_rows)
         layout.addWidget(grp_grid)
 
-        # Taille feuille
         grp_sheet = QGroupBox("Taille de la feuille")
         sl = QHBoxLayout(grp_sheet)
         sl.addWidget(QLabel("Format :"))
         self.combo_sheet = QComboBox()
-        for name in PAGE_SIZES:
-            self.combo_sheet.addItem(name)
-        self.combo_sheet.setCurrentText("A4 Paysage")
+        populate_format_combo(self.combo_sheet, "A4 Paysage")
+        self.combo_sheet.activated.connect(lambda: handle_format_selection(self.combo_sheet, self))
         sl.addWidget(self.combo_sheet)
         layout.addWidget(grp_sheet)
 
-        # Marges
         grp_margins = QGroupBox("Marges (mm)")
         ml = QHBoxLayout(grp_margins)
         self.margins = {}
@@ -57,7 +55,6 @@ class NupDialog(QDialog):
             self.margins[label.lower()] = spin
         layout.addWidget(grp_margins)
 
-        # Gouttiere
         grp_gutter = QGroupBox("Gouttiere (mm)")
         gutl = QHBoxLayout(grp_gutter)
         gutl.addWidget(QLabel("Horizontale :"))
@@ -74,7 +71,6 @@ class NupDialog(QDialog):
         gutl.addWidget(self.spin_gutter_v)
         layout.addWidget(grp_gutter)
 
-        # Options
         grp_opts = QGroupBox("Options")
         ol = QVBoxLayout(grp_opts)
         self.chk_fit = QCheckBox("Ajuster les pages a la cellule")
@@ -88,16 +84,13 @@ class NupDialog(QDialog):
         bg_layout.addWidget(self.chk_bg)
         self.lbl_bg = QLabel("Aucun")
         bg_layout.addWidget(self.lbl_bg)
-        from PyQt6.QtWidgets import QPushButton
         btn_bg = QPushButton("Choisir...")
         btn_bg.clicked.connect(self._choose_bg)
         bg_layout.addWidget(btn_bg)
         bg_layout.addStretch()
         ol.addLayout(bg_layout)
-
         layout.addWidget(grp_opts)
 
-        # Boutons
         buttons = QDialogButtonBox(
             QDialogButtonBox.StandardButton.Ok | QDialogButtonBox.StandardButton.Cancel
         )
@@ -113,12 +106,10 @@ class NupDialog(QDialog):
             self.chk_bg.setChecked(True)
 
     def get_settings(self):
-        sheet_text = self.combo_sheet.currentText()
-        sheet_size = PAGE_SIZES[sheet_text]
         return {
             "cols": self.spin_cols.value(),
             "rows": self.spin_rows.value(),
-            "sheet_size": sheet_size,
+            "sheet_size": get_selected_size(self.combo_sheet),
             "margin_top": mm_to_pt(self.margins["haut"].value()),
             "margin_bottom": mm_to_pt(self.margins["bas"].value()),
             "margin_left": mm_to_pt(self.margins["gauche"].value()),