fix(charts): preserve comparison types and draggable window headings

Keep current lines and historical scatter points in a dedicated comparison chart type. Expose floating headings and use idempotent placement so StrictMode no longer masks production overlap.

src/shared/ui/floating-window.tsx

@@ -1,4 +1,4 @@
-import { useEffect, useId, useRef, useState, useSyncExternalStore, type ReactNode } from "react";
+import { useEffect, useId, useLayoutEffect, useRef, useState, useSyncExternalStore, type ReactNode } from "react";
 import { createPortal } from "react-dom";
 import { Rnd } from "react-rnd";
 import { Maximize2, Minimize2, X } from "lucide-react";
@@ -48,16 +48,31 @@ export function FloatingWindow({ title, triggerLabel, fillContent = false, openR
   };
 
   useEffect(() => () => removeFloatingWindow(id), [id]);
-  useEffect(() => {
+  useLayoutEffect(() => {
     if (!open) return;
-    const offset = (floatingWindowOrder().filter((windowId) => windowId !== id).length % 5) * 24;
-    setBounds((current) => fitWindow({ ...current, x: current.x + offset, y: current.y + offset }));
+    const others = floatingWindowOrder().filter((windowId) => windowId !== id);
+    const headingHeight = Array.from(floatingWindowHost().querySelectorAll<HTMLElement>(".floating-window-heading"))
+      .reduce((height, element) => Math.max(height, element.offsetHeight), 48);
+    const step = headingHeight + 8;
+    const minHeight = Math.min(260, window.innerHeight - 16);
+    const slots = Math.max(1, Math.floor((window.innerHeight - 64 - minHeight - 8) / step) + 1);
+    const slot = others.length % slots;
+    const y = Math.max(8, Math.min(64 + slot * step, window.innerHeight - minHeight - 8));
+    // Keep the preceding headings exposed. Shorter viewports reduce content
+    // height instead of clamping several windows onto the same title bar.
+    // Absolute placement also makes StrictMode's repeated setup idempotent.
+    setBounds(fitWindow({ x: (window.innerWidth - 800) / 2 + slot * 24, y,
+      width: 800, height: Math.min(560, window.innerHeight - y - 8) }));
     raiseFloatingWindow(id);
     if (focusOnOpen.current) heading.current?.focus({ preventScroll: true });
     focusOnOpen.current = false;
     const resize = () => {
       setViewport({ width: window.innerWidth, height: window.innerHeight });
-      setBounds((current) => fitWindow(current));
+      setBounds((current) => {
+        const minimumHeight = Math.min(260, window.innerHeight - 16);
+        const y = Math.max(8, Math.min(current.y, window.innerHeight - minimumHeight - 8));
+        return fitWindow({ ...current, y, height: Math.min(current.height, window.innerHeight - y - 8) });
+      });
     };
     window.addEventListener("resize", resize);
     return () => {
@@ -75,9 +90,7 @@ export function FloatingWindow({ title, triggerLabel, fillContent = false, openR
       aria-label={triggerLabel ?? `放大查看 ${title}`} title="放大查看" aria-haspopup="dialog" aria-expanded={open}
       onClick={() => {
         if (!open) {
-          const offset = (order.length % 5) * 24;
           setViewport({ width: window.innerWidth, height: window.innerHeight });
-          setBounds(fitWindow({ x: (window.innerWidth - 800) / 2 + offset, y: 64 + offset, width: 800, height: 560 }));
           setMaximized(false);
           focusOnOpen.current = true;
           setManuallyOpen(true);