launch huashu-design v1.0: 9 demos + marketing-first README

- 新增 9 个能力 demo（workflow + capability），每个 MP4 + GIF + 60fps
- README 重写：营销 hook 开头 · 功能优先结构 · 自然嵌入 GIF
- 修复 render-video.js Google Fonts networkidle 超时
- 修复 c1-ios-prototype 刘海/Home Indicator 背景色
- 补充 references/editable-pptx.md 和 scripts/export_deck_stage_pdf.mjs

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

assets/animations.jsx

@@ -162,6 +162,12 @@
     const startTimeRef = useRef(performance.now());
     const canvasRef = useRef(null);
 
+    // Recording mode: render-video.js injects window.__recording = true before goto.
+    // When set, force loop=false so the export ends on the final frame instead of
+    // wrapping back to t=0 and capturing the start of the next cycle.
+    // (Browsers viewing manually still loop because __recording is undefined there.)
+    const effectiveLoop = (typeof window !== 'undefined' && window.__recording) ? false : loop;
+
     useEffect(() => {
       function updateScale() {
         const vw = window.innerWidth;
@@ -195,7 +201,10 @@
         setTime(prev => {
           const next = prev + delta;
           if (next >= duration) {
-            return loop ? 0 : duration;
+            // effectiveLoop honors window.__recording (forced non-loop during export).
+            // Stop just shy of duration so the final-frame state stays rendered
+            // (avoids exiting all Sprites that end exactly at `duration`).
+            return effectiveLoop ? 0 : duration - 0.001;
           }
           return next;
         });
@@ -218,7 +227,7 @@
         cancelled = true;
         cancelAnimationFrame(rafRef.current);
       };
-    }, [playing, duration, loop]);
+    }, [playing, duration, effectiveLoop]);
 
     const handleScrub = useCallback((e) => {
       const rect = e.currentTarget.getBoundingClientRect();