feat(sidebar): redesign sidebar UI with three user states (light theme)

Replace the dark sidebar theme with a light-themed three-state UI
matching the design references:

- guest  : pink "login" pill in user row, no status pill on VIP card,
           "Activate VIP Membership" button shown
- member : "VIP membership not activated" subtitle, no status pill,
           "Activate VIP Membership" button shown
- vip    : pink "VIP Member" pill with diamond icon, "Activated" pill
           in VIP card header, no Activate button

Decompose into BackBar, UserHeader, VipBenefitsCard, and VoicePackageCard
under src/app/sidebar/components/. Delete obsolete GuestPanel,
UserInfoCard, and VipCta.

Lift VIP_BENEFITS to a shared src/data/constants/vip-benefits.ts so the
sidebar and subscription page render identical benefit copy.

Add five sidebar tokens (--color-card-surface, --color-voice-gradient-*
--border-card, --shadow-card, --color-pill-bg) to src/tokens/colors.css.

Includes barrelsby regeneration for src/app/sidebar/components and
side-effect barrel updates under src/stores/{auth,chat,sidebar,user},
plus package-lock.json from npm install (required for lint/typecheck).

Co-Authored-By: Claude <noreply@anthropic.com>

src/app/sidebar/components/user-header.module.css

@@ -0,0 +1,130 @@
+.row {
+  display: flex;
+  align-items: center;
+  gap: var(--spacing-md, 12px);
+  width: 100%;
+  box-sizing: border-box;
+}
+
+.avatar {
+  flex: 0 0 auto;
+  width: 56px;
+  height: 56px;
+  border-radius: 50%;
+  background: var(--color-accent, #f84d96);
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  overflow: hidden;
+  color: #ffffff;
+}
+
+.avatarImg {
+  width: 100%;
+  height: 100%;
+  object-fit: cover;
+  display: block;
+}
+
+.avatarIcon {
+  color: inherit;
+}
+
+.text {
+  display: flex;
+  flex-direction: column;
+  gap: 4px;
+  flex: 1 1 auto;
+  min-width: 0;
+}
+
+.name {
+  margin: 0;
+  font-size: var(--font-size-lg, 16px);
+  font-weight: 600;
+  color: #000000;
+  line-height: 1.2;
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+}
+
+.subtitle {
+  margin: 0;
+  font-size: var(--font-size-sm, 12px);
+  color: var(--color-text-secondary, #9e9e9e);
+  line-height: 1.2;
+}
+
+/* "VIP Member" 粉色 pill（含小钻石图标） */
+.vipMemberPill {
+  display: inline-flex;
+  align-items: center;
+  gap: var(--spacing-xs, 4px);
+  align-self: flex-start;
+  padding: 3px var(--spacing-sm, 8px);
+  border-radius: var(--radius-full, 999px);
+  background: var(--color-pill-bg, rgba(248, 77, 150, 0.10));
+  color: var(--color-accent, #f84d96);
+  font-size: var(--font-size-xs, 10px);
+  font-weight: 600;
+  line-height: 1;
+}
+
+.diamondIcon {
+  color: var(--color-accent, #f84d96);
+  flex-shrink: 0;
+}
+
+/* guest 状态下的 "login" 粉色胶囊按钮 */
+.loginPill {
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  padding: 6px var(--spacing-lg, 16px);
+  border-radius: var(--radius-full, 999px);
+  background: linear-gradient(
+    90deg,
+    var(--color-button-gradient-start, #ff67e0),
+    var(--color-button-gradient-end, #ff52a2)
+  );
+  color: var(--color-text-primary, #ffffff);
+  font-size: var(--font-size-sm, 12px);
+  font-weight: 600;
+  border: 0;
+  cursor: pointer;
+  flex-shrink: 0;
+}
+
+.loginPill:hover {
+  opacity: 0.9;
+}
+
+.loginPill:focus-visible {
+  outline: 2px solid var(--color-accent, #f84d96);
+  outline-offset: 2px;
+}
+
+/* ============================================================
+ * 骨架占位（isLoading 时显示）
+ * ============================================================ */
+.skeleton {
+  display: block;
+  background: var(--color-dark-gray, #e5e5e5);
+  border-radius: var(--radius-md, 8px);
+}
+
+.skeletonMd {
+  width: 60%;
+  height: 18px;
+}
+
+.skeletonSm {
+  width: 80%;
+  height: 14px;
+}
+
+.skeletonXs {
+  width: 40%;
+  height: 14px;
+}