feat: 类型帖互动、积分经济与发帖体验

补齐问答采纳/重开、投票匿名与有票禁编、悬赏过期退回、抽奖回帖开奖，并接入积分账本与发帖附件可见性。

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/components/TipHost.tsx

@@ -0,0 +1,135 @@
+"use client";
+
+import { useEffect, useRef, useState } from "react";
+import { createPortal } from "react-dom";
+
+type TipState = {
+  text: string;
+  x: number;
+  y: number;
+  place: "top" | "bottom";
+} | null;
+
+/**
+ * 全站悬停即显提示：监听 [data-tip]，替代浏览器原生 title 的延迟气泡。
+ * 挂在 root layout 即可，业务侧写 data-tip="文案" 并保留 aria-label。
+ */
+export default function TipHost() {
+  const [tip, setTip] = useState<TipState>(null);
+  const tipRef = useRef<HTMLDivElement>(null);
+  const activeEl = useRef<Element | null>(null);
+
+  useEffect(() => {
+    const hide = () => {
+      activeEl.current = null;
+      setTip(null);
+    };
+
+    const placeTip = (el: Element, text: string) => {
+      const rect = el.getBoundingClientRect();
+      const preferBottom = rect.top < 48;
+      const x = rect.left + rect.width / 2;
+      const y = preferBottom ? rect.bottom + 8 : rect.top - 8;
+      setTip({
+        text,
+        x,
+        y,
+        place: preferBottom ? "bottom" : "top",
+      });
+    };
+
+    const onOver = (e: Event) => {
+      const t = e.target;
+      if (!(t instanceof Element)) return;
+      const host = t.closest("[data-tip]");
+      if (!host) {
+        if (activeEl.current) hide();
+        return;
+      }
+      const text = host.getAttribute("data-tip")?.trim();
+      if (!text) {
+        hide();
+        return;
+      }
+      activeEl.current = host;
+      placeTip(host, text);
+    };
+
+    const onOut = (e: Event) => {
+      if (!(e instanceof MouseEvent)) return;
+      const related = e.relatedTarget;
+      if (
+        related instanceof Node &&
+        activeEl.current &&
+        activeEl.current.contains(related)
+      ) {
+        return;
+      }
+      hide();
+    };
+
+    const onScrollOrResize = () => {
+      if (!activeEl.current) return;
+      const text = activeEl.current.getAttribute("data-tip")?.trim();
+      if (!text) {
+        hide();
+        return;
+      }
+      placeTip(activeEl.current, text);
+    };
+
+    // mouseover 冒泡，便于 closest；立即显示，无延时
+    document.addEventListener("mouseover", onOver);
+    document.addEventListener("mouseout", onOut);
+    document.addEventListener("focusin", onOver);
+    document.addEventListener("focusout", onOut);
+    window.addEventListener("scroll", onScrollOrResize, true);
+    window.addEventListener("resize", onScrollOrResize);
+
+    return () => {
+      document.removeEventListener("mouseover", onOver);
+      document.removeEventListener("mouseout", onOut);
+      document.removeEventListener("focusin", onOver);
+      document.removeEventListener("focusout", onOut);
+      window.removeEventListener("scroll", onScrollOrResize, true);
+      window.removeEventListener("resize", onScrollOrResize);
+    };
+  }, []);
+
+  // 测量后微调，避免贴边裁切
+  useEffect(() => {
+    if (!tip || !tipRef.current) return;
+    const el = tipRef.current;
+    const w = el.offsetWidth;
+    const pad = 10;
+    let left = tip.x;
+    const half = w / 2;
+    if (left - half < pad) left = pad + half;
+    if (left + half > window.innerWidth - pad) {
+      left = window.innerWidth - pad - half;
+    }
+    el.style.left = `${left}px`;
+  }, [tip]);
+
+  if (!tip) return null;
+
+  return createPortal(
+    <div
+      ref={tipRef}
+      role="tooltip"
+      className="j13-tip-bubble"
+      data-place={tip.place}
+      style={{
+        left: tip.x,
+        top: tip.y,
+        transform:
+          tip.place === "top"
+            ? "translate(-50%, -100%)"
+            : "translate(-50%, 0)",
+      }}
+    >
+      {tip.text}
+    </div>,
+    document.body
+  );
+}