fix: 四处 router.push 缺 /page 前缀导致 404

HashRouter 顶层路由是 /page/*，所有 workspace 子路由必须带这个前缀
才能命中。以下四处 router.push 字面量遗漏，点击后落到 NotFoundPage：

- skill-evolution-panel.tsx 返回技能按钮
- NewAgentPage.tsx 返回 agents
- NewAgentPage.tsx 创建后“开始对话”
- agent-card.tsx 列表卡片“聊天”按钮

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

frontend-web/src/components/workspace/agents/agent-card.tsx

@@ -91,7 +91,7 @@ export function AgentCard({ agent }: AgentCardProps) {
   ]);
 
   function handleChat() {
-    router.push(`/workspace/agents/${agent.id}/chats/new`);
+    router.push(`/page/workspace/agents/${agent.id}/chats/new`);
   }
 
   async function handleDelete() {

frontend-web/src/components/workspace/skills/skill-evolution-panel.tsx

@@ -50,7 +50,7 @@ export function SkillEvolutionPanel() {
         <Button
           variant="outline"
           size="sm"
-          onClick={() => router.push("/workspace/skills")}
+          onClick={() => router.push("/page/workspace/skills")}
         >
           <ArrowLeftIcon className="size-4" />
           {tt.backToSkills}

frontend-web/src/pages/NewAgentPage.tsx

@@ -326,7 +326,7 @@ export default function NewAgentPage() {
               <Button
                 variant="ghost"
                 size="icon-sm"
-                onClick={() => router.push("/workspace/agents")}
+                onClick={() => router.push("/page/workspace/agents")}
               >
                 <ArrowLeftIcon className="h-4 w-4" />
               </Button>
@@ -336,7 +336,7 @@ export default function NewAgentPage() {
               <Button
                 variant="outline"
                 size="sm"
-                onClick={() => router.push(`/workspace/agents/${agent.id}/chats/new`)}
+                onClick={() => router.push(`/page/workspace/agents/${agent.id}/chats/new`)}
               >
                 <CheckCircleIcon className="h-4 w-4" />
                 开始对话