Make ReminderDialog resizable/wider and fix Options dialog bottom clipping

ReminderDialog: override the shared dialog base's resizable(False, False),
widen the initial layout, and pin the items-table edit row's amount field
to the exact same pixel width as the table's fixed "amount" column (via a
pack_propagate(False) frame) while the description field stretches like
the table's own column does -- keeps alignment exact even after resizing.

OptionsDialog: compute the window's initial geometry from its actual
required size after all tabs (incl. "Mahnungen") are built, instead of a
static guess that clipped the Mahnungen tab's tables/buttons at the bottom.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/ccma/ui/options_dialog.py

@@ -61,13 +61,21 @@ class OptionsDialog(tk.Toplevel):
             )
         }
         self.title("Optionen")
-        self.geometry("900x650")
-        self.minsize(760, 540)
         self.transient(master.winfo_toplevel())
         self.grab_set()
         self.resizable(True, True)
         self._build_ui()
         self.bind("<Escape>", lambda _event: self.destroy())
+        # A ttk.Notebook sizes itself to its tallest/widest tab, so once every tab
+        # (including "Mahnungen" with its two tables) is built, the natural required
+        # size reflects whichever one actually needs the most room -- open at that size
+        # instead of a static guess that clips a table/buttons at the bottom. The floor
+        # keeps the window from opening awkwardly small on short content.
+        self.update_idletasks()
+        width = max(900, self.winfo_reqwidth())
+        height = max(650, self.winfo_reqheight())
+        self.geometry(f"{width}x{height}")
+        self.minsize(760, 540)
         self.after_idle(self._center_on_parent)
 
     def _build_ui(self) -> None: