feat(renderer): Minimap (custom overview, wired to settings.minimap)

src/renderer/components/editor/Minimap.tsx

@@ -0,0 +1,33 @@
+interface Props {
+  content: string;
+  scrollRatio?: number;       // 0-1, where the viewport is
+  visibleRatio?: number;      // 0-1, what fraction of content is visible
+}
+
+export function Minimap({ content, scrollRatio = 0, visibleRatio = 1 }: Props) {
+  const lines = content.split('\n');
+  // Compute viewport position in the minimap
+  const viewportTop = Math.round(scrollRatio * 100);
+  const viewportHeight = Math.round(visibleRatio * 100);
+
+  return (
+    <div
+      data-testid="minimap"
+      className="pointer-events-none absolute right-0 top-0 h-full w-[100px] overflow-hidden border-l border-border bg-card/30 p-1 font-mono text-[6px] leading-[8px] text-muted-foreground"
+      aria-hidden="true"
+    >
+      <pre className="w-full truncate whitespace-pre">
+        {lines.map((line, i) => (
+          <div key={i} data-testid="minimap-line">
+            {line || ' '}
+          </div>
+        ))}
+      </pre>
+      <div
+        data-testid="minimap-viewport"
+        className="pointer-events-none absolute left-0 right-0 bg-brand/15"
+        style={{ top: `${viewportTop}%`, height: `${Math.max(viewportHeight, 5)}%` }}
+      />
+    </div>
+  );
+}