fix(editor): la barre de numerotation de ligne suit le theme (BUG-058)

frontend/style.css

@@ -3592,6 +3592,20 @@ select {
   overflow-x: auto !important;
   max-width: 100%;
 }
+/* BUG-058: CodeMirror paints its line-number gutter with hardcoded light
+   defaults (#f5f5f5 background, #ddd border), so the bar stayed pale in dark
+   themes while the editor body followed the theme. Deriving the tint from
+   `--text-primary` keeps the gutter subtle and makes it adapt to every theme
+   and mode (dark, light, high-contrast, sepia). */
+.cm-editor .cm-gutters {
+  background: color-mix(in srgb, var(--text-primary) 5%, transparent) !important;
+  color: var(--text-secondary) !important;
+  border-right: 1px solid var(--border) !important;
+}
+.cm-editor .cm-gutters .cm-activeLineGutter {
+  background: color-mix(in srgb, var(--text-primary) 10%, transparent) !important;
+  color: var(--text-primary) !important;
+}
 .fallback-editor {
   width: 100%;
   min-height: 100%;