Add share entry to the canvas top bar

The share popover (publish to site, copy link) and publish modal had
no reachable entry; add a share button next to the save status,
matching the reference product's top bar.

components/canvas/LiblibVideoCanvasReplica.tsx

@@ -11092,6 +11092,7 @@ export function LiblibVideoCanvasReplica({
         draftTitle={draftTitle}
         isTitleEditing={isTitleEditing}
         onAccount={() => toggleTopPanel("account")}
+        onShare={() => toggleTopPanel("share")}
         onCommitTitle={commitTitle}
         onDraftTitleChange={setDraftTitle}
         onStartTitleEdit={() => setIsTitleEditing(true)}
@@ -11563,6 +11564,7 @@ function TopBar({
   draftTitle,
   isTitleEditing,
   onAccount,
+  onShare,
   onCommitTitle,
   onDraftTitleChange,
   onStartTitleEdit,
@@ -11578,6 +11580,7 @@ function TopBar({
   draftTitle: string;
   isTitleEditing: boolean;
   onAccount: () => void;
+  onShare: () => void;
   onCommitTitle: () => void;
   onDraftTitleChange: (value: string) => void;
   onStartTitleEdit: () => void;
@@ -11633,6 +11636,14 @@ function TopBar({
         >
           {saveStatus === "saving" ? "保存中…" : saveStatus === "pending" ? "待保存" : saveStatus === "error" ? "保存失败，点击重试" : saveStatus === "unavailable" ? "画布未就绪" : "已保存"}
         </button>
+        <button
+          className="flex h-10 cursor-pointer items-center gap-2 rounded-xl border border-white/8 bg-[#202020]/95 px-3 text-[13px] text-white/78 shadow-[0_12px_30px_rgba(0,0,0,0.28)] transition hover:bg-[#2a2a2a] hover:text-white"
+          onClick={onShare}
+          title="发布与分享"
+          type="button"
+        >
+          分享
+        </button>
         <button
           className="flex h-10 cursor-pointer items-center gap-2 rounded-xl border border-white/8 bg-[#202020]/95 px-3 text-[13px] text-white/78 shadow-[0_12px_30px_rgba(0,0,0,0.28)] transition hover:bg-[#2a2a2a] hover:text-white"
           onClick={onAccount}