build(webui): 按 podman 正常流程重建前端产物并嵌入 Go 二进制

- make web-build（ws-usernode-web-dev 容器）重建 web/dist → internal/webui/dist
- 清空旧 hash 产物，避免 go:embed 冗余
- make build-embed 产出 bin/usernode（22MB，含新主题前端）

internal/webui/dist/assets/UserLayout-BL5gffot.css

@@ -0,0 +1 @@
+.user-layout[data-v-a89182e3]{min-height:100vh}.header[data-v-a89182e3]{height:var(--app-header-height);display:flex;align-items:center;gap:20px;background:var(--el-bg-color);border-bottom:1px solid var(--el-border-color-light);box-shadow:0 1px 4px #0f172a0a}.logo[data-v-a89182e3]{display:flex;align-items:center;gap:10px;flex-shrink:0}.logo-icon[data-v-a89182e3]{width:32px;height:32px;border-radius:9px;display:flex;align-items:center;justify-content:center;color:#fff;background:linear-gradient(135deg,#6366f1,#8b5cf6);box-shadow:0 4px 12px #6366f166}.logo-text[data-v-a89182e3]{font-weight:650;font-size:15px}.nav[data-v-a89182e3]{flex:1;border-bottom:none}.header-right[data-v-a89182e3]{display:flex;align-items:center;gap:10px;flex-shrink:0}.icon-btn[data-v-a89182e3]{color:var(--el-text-color-regular);padding:4px}.user-chip[data-v-a89182e3]{display:flex;align-items:center;gap:8px;cursor:pointer;outline:none}.avatar[data-v-a89182e3]{background:linear-gradient(135deg,#6366f1,#8b5cf6);color:#fff}.main[data-v-a89182e3]{padding:20px;background:var(--el-bg-color-page)}