feat(bandmap): drag the width, and remember it

Both band maps were pinned to a hardcoded width — 300px docked beside the
tables, 260px per card in the Band map tab. On a busy band the map could not be
given more room, and on a quiet one the log could not take it back.

The docked map becomes a resizable grid column with the grip in the gap between
the panes, so the handle costs no space; the tab cards share one width with the
grip on their right edge. Side-by-side columns of different widths read as a
mistake rather than a choice, which is why the tab has one width and not one
per card. Double-click either grip to return to the default.

The drag measures from the pointer's START position rather than the container,
so the same helper serves both edges — the docked map sits on the left or the
right depending on the operator's setting, and the grip is on its inner edge
either way. Pointer capture, like the main splitter: without it the map or the
grid under the cursor swallows the moves.

Both widths are persisted through writeUiPref and registered as portable, so
they travel with the data folder like the main splitter and the rest of the
layout.

changelog.json

@@ -1,4 +1,14 @@
 [
+  {
+    "version": "0.24.1",
+    "date": "",
+    "en": [
+      "Band map: the width can be dragged. Both the map docked beside the tables and the per-band cards in the Band map tab were locked at a fixed width, so an operator watching a busy band could not give the map more room — nor take it back for the log. Grab the edge to resize, double-click it to go back to the default. The width is remembered and travels with your data folder, like the other layout settings. In the tab, one width applies to every card: they sit side by side, and columns of different widths read as a mistake."
+    ],
+    "fr": [
+      "Band map : la largeur se règle à la souris. La carte ancrée à côté des tableaux et les cartes par bande de l'onglet Band map étaient figées à une largeur fixe : impossible de donner plus de place à la carte sur une bande chargée, ni de la reprendre pour le journal. Attrape le bord pour redimensionner, double-clic pour revenir au défaut. La largeur est mémorisée et voyage avec ton dossier de données, comme les autres réglages de disposition. Dans l'onglet, une seule largeur vaut pour toutes les cartes : elles sont côte à côte, et des colonnes de largeurs différentes se lisent comme une erreur."
+    ]
+  },
   {
     "version": "0.24.0",
     "date": "",